Apply a pre-m to perevent weed seed germination (use tupersan or tenacity if you want to overseed). Apply an N fertilizer monthly (starter fert can be used) as during the first year, a new lawn needs plenty of food. Water regularly when there is no rain. Spot spray any existing weeds with WBG or if you overseeded use Tenacity untill the germiated grass has been mowed a couple of times. Winerize at the end of the year and then use standard schedules for fertilization starting next year.

I'll answer your plant questions: Pic 5 = Lilac (Can be grown as a small tree or shrub depending on your preference). Pic 6 = Boxwood. Appears to have been sunburnt/exposed to drought and poorly manicured (if ever). Cut off the dead stems, it may come back. Boxwood is cheap if you want to replace it. I'd suggest trimming them all to give them a uniform shape and promote center growth. Pic 6 = Weed. Clip all those seed heads off and throw them in the garbage before they spread everywhere! Then pull it or spray it. Congrats on the new place!

Livestock do not damage soil. Lack of livestock damages soil by stopping the nutrient cycle, allowing weeds to move in, and by not providing enough disturbance. Most tree huggers and even many ranchers do not understand that disturbance of the soil is a necessary requirement for continual renewal of the soil. It is required at least annually to keep a pasture in good condition for grazing. I would be much more concerned about the prolonged lack of animals than any possibility that a horse, or even a large herd of horses, might damage the soil. Livestock grazing and even stampeding is one of the best things you can do to plant seed. Mother Nature uses that as Her preferred method for replanting the prairies of the world. Farmers are learning the method, too. One rancher here in Texas borrowed a neighbor's 800 head of cattle to eat down an overgrown pasture of about 50 acres. If you know anything about cattle, it took about 24 hours before the land looked like the surface of the moon. Every plant was gone either eaten down or trampled down. He didn't do anything else and the grass started growing immediately. The next season started out with an abundance of fresh grass where once stood a mess of grass and browse. But anyway, if you do not have a ready supply of livestock located conveniently on the other side of one of your fences, then you will need some equipment to grade for your house and then regrade, after the builders leave, for your garden. The tool the graders will use is called a box blade and it sits on the back of a tractor. A good grader could grade 4 acres of pastureland in a morning if there are no obstacles. If there are buildings, concrete, sprinklers, roots, or other things in the way, it could take as long as 2 days to get the last details. Rule of thumb for trees: the roots will extend to the edge of the tree canopy. Some smaller roots may continue beyond the edge of the canopy. Do not turn the soil over. Mother Nature never turns the soil over. That is the worst thing you can do in preparation for anything you have planned. Definitely don't do it for under the house, and don't do it for the lawn. The box blade is all you need. If the driver feels the need to use the ripper bars on the box blade, at least that tool is under control. Other tools that dig or till the soil will cause an increasing bumpiness problem for three years. After that the soil will have settled and you can level it. Thank you for writing before you made any mistakes.

The best solution would be low volume drip tubing and shrub bubblers although it may not be the most economical. You would not need a massive pump to supply the water needed but to run pipe underground with wiring to the valves could become very pricey on 7 acres. If all the areas you want watered are relatively close and not sprawled out this would be the route I would take.