I am in the process of replacing a window, in my 60 year old brick home. It too has 1x4's around the window openings. The brick comes within 3/4" of the 2x4 framing. The 1x4 adds another 3/4" - so there is 1 1/2" reveal for the brickmold. I'm using this 1 1/2" for the nailing flange on the window.

Certification is a nice touch because it does indicate that someone has gone the extra mile to get certified, however, most of the best installers that I know are not certified. Most of them are too busy being busy and installing. I would not base my decision one way or another on this.

I'd simply ask what experience he has installing the windows you are considering. "Factory Authorized" installer may not mean anything more that someone sat through a 5 hour course. I would lean heavily towards someone with a lot of experience with whatever window you end up choosing.

You said you've already made a decision but for others in the future....transoms in a bedroom complicate window coverings. We are renting a house with plantation shutters on the windows and nothing on the transoms. Dawn is pretty darn early in the summer! If you are a late sleeper or need to sleep during the day, consider how to cover the transoms.