Historically significant home?

[Significant]

We're in the process of buying our first home, a 1920s Sears kit house, in Vermont. We're going through Rural Development for financing, and got some estimates on replacing the 13 old metal frame windows throughout the house. Since RD is a federally-funded loan program, our RD caseworker (if that's the right term) tells me we have to get 'approval' from the State historical preservation board for vinyl replacement windows. In the even that, after 30 days of research, they discover that our home-to-be is "historically significant," we will need to follow their guidlines as to what kind of windows we can get or if we can replace them at all.

I'm having a devil of a time finding out 1) why the historical preservation board needed our windows estimate before doing their research on the potential house; 2) what guidelines they use to determine historical significance; and 3) if we can just hold off doing the windows now so we can close on the darn house and then save up to do the windows ourselves, on our own terms, at our discretion.

Any thoughts? Anyone run up against this? The house is, as I mentioned, a kit house from the 20s, has asbestos siding, new-fangled French doors with blinds in-between double panes of glass, and a sparkling new stove-pipe running up through the soffits already...talk about your NON-historical alterations.

Thanks for any input!