What is the right way to restart bitcoind if it crashes? I am very new to this and apologies if it has been asked before but I can't seem to find a clear answer after looking extensively.

I am trying to run a full node. I started bitcoind -daemon and everything worked fine, the blockchain was syncing. It crashed the next day because I hadn't set my options for swap memory correctly.

After fixing that issue, I did bitcoind -daemon again and it looked like everything was being done from the start. Should I be doing bitcoind -reindex-chainstate from now on if the process stops? Or did I not understand correctly and simply doing bitcoind will resume syncing but requires some verification first?

Also, in any of the above cases, is it the same process once the blockchain has synced?

This is on a Raspberry Pi 3B+ with an external HDD for storage.

Thanks a lot in advance.
If you check in your debug.log you should be able to see if there is any error when you started the node. Probably when the node shutdown uncleanly some of the tables were in an inconsistent state.

Presuming everything is fine and it is not stuck, it is okay to just start with bitcoind -daemon and it will do what it needs to.