Sounds like you are thinking it through.
Velvet will pass some light. Check it out before making a major commitment. You may need to add some light blocking liners to the curtains. I have found that the Eclipse brand curtains are fairly effective. You will be surprised how much light passes around the edges, even with big overlaps. Just be prepared to plan for it.
I stand by the recommendation to get a tensioned screen if you can afford it. Go smaller if you must, but long term you will thank yourself. You might want to consider a gray screen to improve black levels at the expense of overall brightness, but I actually think you will be OK.
Colors look good. I used eggshell on the walls. There are some reflections, but it was vastly improved. The really critical area is the ceiling for the first 6' out from the screen.
There are several good threads here on constructing acoustic panels. Dense fiberboard is probably not the best choice. Read and research.
22' will get you 2 rows, but you need to plan for that. You will definitely need a riser for the back row. It will most likely be about 10-12" high. Otherwise the folks in the back row will mostly see seat backs and heads
Watch for deals on seating. The k-mart deal is now over, but Costco is currently running a powered theater seat deal. You can expect the Costco deal each year right after Christmas. The other stuff comes and goes, but it usually gets reported in the accessory forum pretty quickly. If you decide on mainline seats, look here for online dealers. Furniture stores charge at least 50% more and often triple. I bought mine from Roman and couldn't be happier.
Back to those speakers. It really is a personal choice. The room is modestly sized, so reasonable speakers can work. Look at efficiency. An inefficient speaker makes the amplifier work harder, thus you need a bigger amp. However, they tend to be smoother in response. As I said, I am a Klipsch fan, so I would be recommending you look at their towers or better still, scour craigslist for some nice KG series or Cornwalls. But that's just me. You really do need to go listen before committing as this is a very personal decision. You need to find a store with decent listening rooms and that is tough these days. Best Buy puts speakers out on the open floor with 30' ceilings. The sound is totally useless for auditioning. One thing to consider is that Amazon has a good return policy, so you can audition and return if they don't feel right.