Yes but we already do that if you attach a wallet that supports spending. We support NWC, LNBits and LNC under that category for now. I use this to connect my LND node via NWC and zap stackers. For security and trust reasons (we don't want to become a juicy target and don't want you to need to trust us), the spending permissions are only stored on your client.¹

Yes. It's basically a test to see if the Lightning network can deliver micropayments which was one of its promises. I am currently basically cheating since I have a private channel to SN so I have actually zero fees and no routing failures but I suspect the majority won't want to open a private channel to SN just for SN.

However, I think zapping on nostr already validated that micropayments over lightning can work. We're just going to iterate on what nostr is already doing but with better UX. We're trying to stay as close as possible to the familiar UX of SN. Ideally, you wouldn't be able to tell any difference if you zap with fee credits or real sats with an attached wallet.

What do you mean with "run up credit"? You mean that they would pay via their zaps? So basically have a negative account balance until they get zapped enough? That's an interesting idea ... 👀