1. You can recover your ecash from Minibits with any other ecash wallet if itsrecovery fits you better.
2. Minibits keeps your seed as provided if you recover full balance. Minibits keeps your existing wallet seed if you do "Wallet address recovery" from Settings. There are good reasons why.
3. NWC works only if you have push notifications enabled and working on your device.
4. Nostr zaps are always settled over lightning. Fees are defined by the network nodes routing the payment, not by Minibits.