First off, taping DMB from that distance will likely be a disaster because the fans are just too loud to get a decent non stack tape normally. Try it because its fun, but don't expect perfect results, I just enjoy the show if i'm out of the 100 level seats. That said.
A. For DMB especially, i'd run hypers. A good hyper mic is the AKG 393, found used they can be had for $375-400. The studio projects C4's are good mics but don't offer the hyper pattern yet. However you can pick these up anywhere from $175-300 depending on used or new. The c1000's don't require shockmounts, they are internally shockmounted.
B. The UA-5 is a good choice, you'd have to find one used, either do the digimod yourself or buy a digimoded one from someone here. I'd look at about $200-$250 for a regular digimod, not performance modded by busman or oade.
C. The archos mini doesn't accept a digital signal in, which means you could run the UA-5 but the signal goes through the A/D back to a D/A, an unnecessary step. I would look into a nomad jukebox 3, or an iriver ihp-120 with rockbox and ditch the archos. Alternatively you can run the UA-5 (or many other USB pre's into a laptop if you have it)
D. If I were you this is what i'd do. I'd get rid of everything you have and buy a pair of SP-CMC-4 or 8's. Basically AT853's or A943's (you have the AT831's), with the phantom power option, and run them into a Denecke PS-2 > AD-20 combo > jb3, or if you really want to keep your archos use a Sound devices mixpre/mp-2/shure fp-24. This combo is nice because you can get Card, Omni, Hyper, Shotgun, and Subcard caps for the mics, when phantom powered they sound really nice, and are stealthable, so you can use your rig for both. Many nice DMB tapes are made with these mics.
Also you can run these mics into a Church audio 3 wire pre, which I highly highly recommend if the gear is too big for you to stealth.
Any questions ask!