If it's worht a couple thousand - it's worth taking good care of! IT might be smart to get a pro involved, but I would recomend shopping around, and I still believe Michaels and similiar shops are usually overpriced. Try looking in the yellow pages for a small local shop.
Fine art should not touch the glass - correct.
A mat will keep the work from touching the glass.
Acid Free matboard and foamcore are both good ideas, for fine art.
Most drymounting I have used should be done by a professional - using an iron is not a good idea. Drymounting is often done with a machine that uses either pressure or suction to insure the piece is very flat and there are no air bubbles - special teflon boards should be used also to make sure the piece does not rub against the drymounting machine. Finally- Drymounting work that is worth a couple thousand could be dodgey - most drymount glues can not be removed, adn those that can - well I have had mixed success with those. If you drymount it - ask lots of questions to make sure it is what you want.
Real glass vs acrylic- I prefer real glass, but on big pieces - it scares me to hang a big piece of sheet glass, so I will sometimes use acrylic. Acrylic is lighter and does not break easily, but it tends to bend and go a little convex - which looks funny to me. The UV blocking and non glare options are good for both acrylic and real glass. They increase the price significantly - but they can be a goood idea, depending on where the piece is going to hang and what kind of light is in the area. In my house most of the frames have real glass, and only two have non glare glass. Personally - I don't like it - unless the frame is near a window and is hard to see without the special glass.
Last word on glass- if it is a big piece and you use real glass with a metal frame - be careful! Most metal frames don;t offer a lot of support by themselves, so tension and pressure (from the frame hangin gon the wall) will go to the glass and backing board quickly. Make sure you hang large pieces with lots of support....
You have the right idea as far as metal frames goes, they can be put together very easily. While I have never priced frames on Dick Blick - I think of them as a good art supply company.