1) My understanding is that LN is better suited for smaller tx, not so much for larger ones. Would it be a problem to send and receive 0.1 BTC on LN? What can I do to push back against those restrictions?
Many LN wallet have default 0.16BTC capacity, so you should able to send/receive 0.1BTC. However you could face routing problem since there aren't many LN channel with such big capacity, which force both party (you and buyer/seller) to make new channel instead.
2) I believe if you are not running your own node, your LN sats are all custodial. And my living situation doesn't allow me to run my own node. Is there a safe way to use someone else's node for a lot of coin coming in and out? Like 0.3 BTC per day, and 2 BTC per week?
There are light non-custodial LN wallet out there such as Electrum. But you either have to,
1. Run your own watchtower, usually on VPS.
2. Use someone else watchtower, either free or paid.
As reminder, watchtower is needed to prevent cheating by broadcasting earlier state of LN channel on Bitcoin on-chain network.
