I'm in a similar situation

1. Even really novel projects have large chunks of glue code and boring infrastructure that the novel bits depend on. claude means I spend 10% of my time on the borng stuff and 90% of time on stuff I previously onky had 10% of my day to work on. In my experience the software picked up our idioms fast and for context, we have a skill file explaining code standards.

2. codex and gemini are comparable when paired with a good harness (pi.dev). if things ever get really bad, I'll drop 8k on a dedicated agent coding server and run it locally. I tried it recently with my current system and it was sub par but I was running a drasticly simpler model.