Even without a picture, I don't see why flowering trees wouldn't work. I'd choose smaller trees and group some of them--you might consider redbuds (Cercis), Halesias, fringetree (Chionanthus), Serviceberry (Amelanchier), witch hazels (Hamamelis--more shrub like) and perhaps some other large shrubs as well--viburnums offer a wide choice. In your zone you could also use some crape myrtles.

You definitely don't have room for a (parking functional)circular drive at the front, and in any case this wouldn't fit 4 cars. If the alley is also driveable, your best best with least amount of additional paving to be added would be to also enter at the back with vehicles, and maybe add a garage/storage shed at the back property line. Otherwise, you don't have enough room to park cars side by side at the one side driveway either, and if you don't want to pave over the front, you will need to have cars drive all the way into the back for all of them to park off-street, and yet not block each other getting in and out. I don't see how you can realistically accomodate even 4 cars off-street without paving over most of the back yard. If parking in the back for 4 cars is the desired solution,you might also consider using a product like turf block instead of solid paving, as this can be turfed, still looks green, yet also allows vehicles to pass over it. This may not be as commonly used back east, but is a good solution in California gardens where you need off-street parking, but still want it to look like softscape rather than hardscape. As to your question about the back stairs, the long run of stairs across the back could be switched out with a staircase that extends out into the garden and then doubles back on itself, to avoid closing off the middle window. It would also be more expensive to rebuild the deck to enlarge it and reorient the stairs, but if you have the budget, it could make for a nice useable space at the top level, and a more aesthetic stairway down to the garden. You'd probably benefit from having a good site planner/landscape designer/landscape architect familiar with what is permitted in your area, to help you think through various alternatives to your dilemma. I've handled similar situations here in California where a duplex was being turned into condos, and the backyard garden design needed to allow access all the way into the back for potential parking. In my case, the actual garages were at the back lower level of the units, but had been turned into living space/offices/storage, and not really intended to be used for vehicles. We also had a similar even more narrow driveway at both sides of the units. The reality ended up being, we added a gravel driveway and flagstone patio that could allow for access to the garages, but only 2 cars parked on site at street driveways,(forward of the house), and the others parked on the street. The long driveways became additional garden space, while also keeping the paving to allow car access if necessary. Your other question about unclear entries is probably best resolved with a permanent decorative address sign with arrows at the juncture point of the combined walk, or at the corner of the house. The one walkway from the street and the second unit's doorway that doesn't directly face the street would make it confusing for first time visitors. Alternatively, why not add bolder street numbers near each door, and make sure they are also lighted up at night. Oh, congrats on the new house purchase, and I hope you enjoy playing with the new house and garden layout...

The gravel wont damage the edger or the blade, but you will tend to throw rocks. On the one hand a reverse rotation blade like Craftsman and a few others make has the advantage of throwing any debris or rocks away from the operator. On the other hand, nothing slows or knocks down the rocks, which can be dangerous to others within about 50 feet (and to cars and windows). I would recommend a rear throw edger with a large blade guard and an addition rubber flap to control throwing rocks. I currently use a Little Wonder 6032 in Jersey, and before that in Southern California had a succession of McLane's and Power Trims. It think Little Wonder and Power Trim are among the best, but both are pricey (starting $500 and running to about $900 for commercial model with Honda GX engine). McLane is probably better value for the money (for home use) and can be had for about $350 to $400. Make sure you get the 801 or 101 models. The 137 is only slightly less expensive, but has been "dumbed down" considerably, and I cannot recommend. Lastly, I would avoid either the edgers with vertical shaft engines and twisted drive belts. IMHO they are junk. Also, the little 2 cycle edgers with the tiny 1hp engines are little more than toys. Stay away.

My custom-designed home in Maine has pink insulation on the parts of foundation that go below ground as the foundation slopes down to a beautiful water view. Pink foam insulation up here is not just for the manufactured home! I have very few moisture issues from my actual home, although strong sea fogs move through our southerly open windows to the point that it causes ink to bleed into the paper. When I consider the power of the moisture off the sea, I am grateful for that pink insulation that at least protects us from moisture from the ground. I also have gravel surrounding the house to help with water runoff, and I am grateful. We did not build this house. But, I can say that one point of great relief is the fact that the house seems to handle outdoor water very well. Mainegrammy, I would carefully examine your options before just removing the gravel. I understand your desire to turn it into garden, as I had the same desire with our current house. Considering the considerable moisture I have off of the ocean, I am extremely thankful that i do not have moisture issues with my basement. I can't give you much good advice, with the exception of "wait and see." If you just bought the house, then it would be to your advantage to live in it for a while (2 years?) until you had an idea of what happens in torrential rains, snow melt, etc., and were familiar with your particular house's surrounding. For example, I have had mold issues not from the ground, but from the moisture off the water in summers with excessive rain (2014). I have learned that if I see a huge bank of sea fog coming OR a stretch of days heavy with rain, I have two choices: clean up mildew from moisture in the outside air, or shut all the windows and keep things dry. If I shut my windows, then things stay amazingly dry. Just examples of what I have learned about my house that surprised me. Before you remove gravel, live in the house for a bit, watch and see how much it is needed. Our gravel is only really important on certain sides of the house. Wait and see what is the case for your house. Your house sounds wonderful. Wish i could see it! And, kudos for living in zone 4. I LOVE winter. You will have some beautiful snowy vistas to see. Please keep posting the New England forum. It's a great place for help and feedback! In the meantime, I'm having a hard time picturing EXACTLY what your gravel situation looks like. If the gravel extends too far into the area where you want to garden, start with a pot garden. They can look extremely attractive, and give you time to figure some things out.