^ The topic of mounting microphones has been/is covered ad nauseam here on these boards, but the quick rundown:
- If you're clamping to balcony or hand rails, basically to anything except a stand, shock mounts are a necessity. You only need one ADHD case banging away on the railing you're clamped on to ruin your recording. After trying out a multitude of solutions the Rycote InVision mounts (the INV-7 model is very versatile) are, to me, hands down, the best. The price you pay up front (~$65 per mount; you'll need one for each mic) is a pittance for the quality product you buy. Lightweight, nearly indestructible, and very good at isolating your microphones, it's a no-brainer, IMHO. Be sure to use the cable clips on them to limit vibrations coming though the cables themselves.
- As far as using shock mounts when mounting mics on a stand, some tapers swear that they've never had issues when using just regular microphone clips (like the AKG SA 60) and that logic seems sound in that the stand itself could possibly attenuate some vibrations. That's all fine and dandy until some drunken fool or wook stumbling through the crowd grabs your stand to keep from falling or decides to shake it in time to the music.
Personally, I always use shock mounts. To me, it's cheap insurance.
The K&M 23510 is a fine mic bar; the K&M 23550 is even simpler. You can spend hundreds on more sophisticated solutions but either of those bars will work just fine for a stereo pair.