Hey, internet came back up.. and Page answered most everything.
Parallel compression works well to bring up the low level passages and details of acoustic recordings in a natural sounding way. I find it much easier to apply than top-down compression while retaining transparency.
Typed earlier..
About all I can say for sure is that audience applause is likely to be the loudest source. Horns might be louder if close. As a general starting point, set gain to where your own loud clapping near the mics is just at or under peak and fine-tune from there if necessary.
The mics you have should work well. If the bigness of 'big mics' is not a problem, run the TLs. They'll be great for this and give you the possibility of different configurations depending on the room and crowd situation. Plus they are very transparent and will sound great on these acoustic instruments. They will also impress the musicians and gain you some respect, warranted or not! They look 'serious'.
Diaphragm size has nothing to do with sensitivity, a microphone with a large diameter capsule may or may not be more sensitive than a small diaphragm mic, but as a class, large diaphragm mics are quieter than small diaphragm mics in general. Classical music recorded up close is more dynamic than amplified music, and often has very quiet passages that hover around the noise floor of the room, so your concern is not unfounded. However, mic-self noise of any of your mics isn't likely to be a problem recording in that kind of venue. No problem on that account with your AKGs, but personally I'd still choose the ADKs.
Skip the TFB-2s. They are quite good relatively inexpensive omnis for less than loud sources, but you have plenty of omnis already with the CA omnis, DPA omnis, and TLs.. plus the TFB-2 can be prone to picking up electrical interference in the cable (at least the pair I have, made in ~2005 are). The gain of your preamps is clean enough to use any of your mics.
As for microphone configuration, a lot depends on the room. Omnis are great and very natural sounding on unamplified acoustic instruments especially, but if the room sounds like a concrete bunker with a cocktail party in it then omnis may not be the best choice. The musicians will probably be arranged in something of a semi-circle and the open side is often an obvious and good place to put the mics. If the ambience sounds good from there then spaced or baffled omnis would be a great. In a good room, Blumlein can be great if the ensemble is small enough to fit within about a 110-degree angle as seen from the mic position, but that’s accumulating a lot of ‘if’s. If the room is less than great sounding and the crowd noise is significant, then a more directional configuration like ORTF from the same position would probably be more appropriate. The ADKs can do any of those well. Your situation sort of spans two worlds: classical ensemble and bar recording, somewhat of a tough cookie.
Unless there is a trip or drink spill hazard, I'd just place them on-stage down low, facing upwards somewhat towards the musicians. That is probably the most practical place anyway. Standard practice is above pointing down, but unless you are high enough or farther away, violins and violas can sound loud and harsh from above, and you will need to be relatively close to get strong enough direct sound in your situation. Although professional classical location recordists will scoff, below shooting up under the music stands can work nicely and sound balanced. Don’t worry to much about music stands being in the way, they always are, but are rarely that much of a problem IME.