I would recommend separating the lightning node from your regular wallet (use cold storage etc). But you can point your wallet that has the features you want to your node and share it with lightning channels. Primarily just use the hot wallet on the umbrel for channel management.

This.

Yeah, this is to bootstrap the zapstore. They encourage devs to take over and I think they have a handoff process.

Projects this size usually have different "areas" of code. Some need to update often for maintenence and support. Other parts are relatively static and only change for large features or architecture changes. So it depends is the correct answer. I'd say for "normal" projects, 2 devs could handle this.

Does anyone need some inbound liquidity? I have some free sats to open a channel. No promises on uptime, I've been having some issues keeping my node up.