What makes you think the roses are gonners? Maybe i can't see from the pictures but what i do see is they are not doing as well as the other big one but they dont look dead to me...they have nice green foliage on them and appear healthy, but maybe they just appear that way in the photo. It seems where the large one is there are not alot of flowers around it, but the two that are not doing well seem to have alot of flowers around it and maybe it is not getting what it needs with all that is in there. I don't know i am a far cry from a expert, guess i just hate to see a rose bush bite the dust...my husband would have a million if we could he loves them! I am probably gonna catch three kinds of hades, but i think i would remove everything but the rose bushes in that particular bed, you can plant elsewhere or give them away if your not gonna use them. Then i would plant a perennial toward the front in between the first and second and the second and third roses...one that has a nice circular uniform shape and maintains it...you said virtually maintenance free right? If it were me i would plant a few hosta's there but when i have suggested that in the past there have been people that said they can't imagine them growing in the same area...but i do mine and my hosta's are huge and my roses flourish...i am in indiana though and it may make a huge difference as to where you are.

While as with all trees results are going to vary with site conditions Betula nigra is genetically a full sized tree - I think it is too large growing for the planting sites you are showing here. For example Seattle has one with an average crown spread of more than 62' (measured ~2005), with the largest known examples (elsewhere) being on the order of 120' tall with trunks about 5' thick. You do want something of some size to match the scale of the house but the magnolia will get big enough to do that if it does well. If it is not a superior named cultivar with a tall habit, fully evergreen foliage presentation (more than one example of these has been on the general market in recent years) I would replace it with one, as they are much more attractive than the shrubby, nearly deciduous version that drops all but one or a few leaves here and there. Another thing I would like to point out is that your house has a geometrically symmetric facade which means that this is one instance where a formal planting with matching pairs and shearing etc. is actually what is called for. A pattern mirroring the design of the front of the house on the ground in front of it and consisting of plants and other natural materials like stonework is what will best serve to integrate your house with the large lawn, which introduces a pastoral feeling. It would also be better to have the plantings extend out from the house more - and perhaps concentrate around the building less - even if the facade was not geometric.

There is some atrocious advice being given here regarding the performance and longevity of replacement windows. A quality product will last 3 decades at minimum, and bring substantial improvements in energy efficiency, functionality, sound mitigation, etc. There are terrible products on the market to be sure, but lumping all new windows in with the lowest common denominator is incorrect, and poor logic... That being said, I would probably agree with the ultimate recommendation of some of the others, and that would be to perform some restoration work on these units. That is assuming that there is historical relevance to the home (sounds like that is the case), where changing out windows and other updates would be detrimental to the value of the home. If you were inclined to replace the windows regardless, there is no reason to move away from double hungs despite the size, and something that offers a similar look would be best.

"there is about 8' from the porch of flat ground for a new landscape design." I see an issue here that I don't think has been thought through. By removing the steps to the left of the porch, you need a new walkway across the front of the house. A comfortable walkway is going to need to be a minimum of 4' wide to not look or feel severely undersized and with a house and yard the size of yours, 5' would be better, which only leaves you with about 2'-3' of planting room if the plants won't be right up against the porch or spilling into the walkway. If you move your walkway a bit further from the house, you will need to deal with the slope, but it will give you a more reasonably sized planting bed and might improve access to the walkway if cars are ever parked in the drive. I don't know what your budget is, but this might be a situation where getting a professional on site will result in a much more useful and aesthetically pleasing solution. The current snowy photos (or in fact most photos) make it difficult to evaluate the actual grade and how the plan will need to be adjusted to accommodate the contours of your lot. If this plan is strictly DYI, you could put a 5' wide walkway close to the house and then put in a planting bed a bit further down the slope and a simple groundcover along the walkway down to the planting bed. If the planting bed is filled with relatively low plants, you will still have good sight lines to the front door and steps. Be sure to make a landing at the base of the steps up the center of the porch.