Before spending any money, I'd first come up with a plan to prevent the aforementioned damage by students from occurring again. Otherwise, you're back to square one.
Second, I would definitely consider taking some of this windfall you seem to have and hire a local consultant to walk you through buying, building, and installing this
system. Blown speakers can be repaired. If the cabinet is decent and a
driver's blown you can often get replacement parts. Or if it's your amps, you might be trashing good speakers for the sake of spending money.
The BLX is definitely the low-end of the
Shure market, but I've used them extensively in radio-heavy environments (with both the PG58 and BLX1's) without much trouble. In fact the only interference I've ever had was from a guitarist running his own BLX for his guitar on my frequency (which was annoying). That being said,
Shure (and AT and
Sennheiser) has a tool on their site to check out the frequency bands and any reputable dealer will help you determine which bands you need to occupy and which model you need to buy to make it work. They are programmable, but not as much so as you'd get from a box that cost more money, they have different submodels that operate within certain ranges of the legal frequencies, you have to figure out which submodel makes sense for your application.
If your dealer won't do that for you, go find someone else to buy from. I personally have had a lot of luck with
Audio-Technica, specifically their ATW-3000
line. They sell a really nice headworn omni that works great for high school (and younger) kids and it costs $130 to replace when it inevitably dies (hopefully after a couple years or more). I have also had a positive experience with their customer service.
The Ultramizer (not exactly sure what that is) sounds like one of those "sonic maximizers" that really just
roll up the 150hz range and
pull down everything except the 3-4kHz band. I don't know if this is the same box, but I had a friend try and convince me that it's better than a graphic eq, and I remain unconvinced. A nice Behringer 31-band EQ will cost about the same. Not sure why you need 6 of these things? Other options if you wanted to bi or
triamp or even just run more than two reinforcement speakers would be a
DSP. There are several on the market that work well, but I like the DriveRack series from dbx.
Bose is not a name you frequently see in sound reinforcement, I would be cautious around anyone purporting it to be worth the money they want for it. I haven't bought PA horns or woofers in some time, but those numbers seem awfully high compared to what you could find from JBL or EV
etc.
The walls are concrete, and the the ceiling/roof if metal and slope upward towards the where the
stage usually is.
You can put the best
system money can buy in that box and if it's not tuned right and the walls are untreated and the
speaker placement isn't considered it's going to sound bad and you will be sad. If this is only two shows per year, what happens the rest of the time? I find it hard to think that the building just sits vacant the rest of the year. Where will the gear be stored? Can it be locked up? Does it need to be loaded out and mothballed?
Again, I really stress taking some of that $20,000 and putting in the pocket of someone who knows what they're doing and lives near you. Check references, visit their projects and observe their work. Talk to the people who have to use the equipment they spec'd 3-4-5 years down the
line. Make sure the consultant knows what you need and can deliver. There are no shortage of
snake oil salesmen, but a lot of these guys will give you the whole package and set it up proper and then train your staff how to keep it running top notch.
) 
