30 metre twins seems odd. The main advantage of twins for alpine climbing over a light single rope is abseil range (plus redundancy against stonefall/sharp edges etc) but for that one normally has 50s at least, or these days increasingly 60s. I struggle to see what advantages a pair of 30s would have over a light (9mm, these days) 60 metre single.
For *twin* rope technique (as opposed to half/double rope technique as practiced in UK trad climbing) it is absolutely normal and standard - at least in the Alps, US practice may differ - to clip both ropes as one. Neither rope makers nor the German or Austrian Alpine clubs recommend anything else.
Regarding abseil/rappel technique: twin ropes, esp. when new, are thin & slippery. Watch out for this first time down, and be sure to use a backup prusik as you always should anyway.
(I grew up with UK trad climbing on double ropes, do some sport & gym climbing on singles, and recently started doing multi-pitch bolted stuff in the Alps on twins)