I'm going to try and replace the original windows in my 30-year old home, on
my own, with vinyl replacement windows - I'm going to try doing one in the
back of the house, see how it goes, and either pay someone to do the rest or
finish the rest myself. I'll be using the Lowes \ HD vinyl replacement
windows.

Two questions:

1 - Once the replacement windows are in, do I have to use exactly the same
size trim? The existing trim is ripped something-or-other - I'd rather use
standard sized pieces.

2 - Should I use treated lumber or untreated lumbar?

I'm going to have the entire house repainted after I finish the windows.

Thanks!