It's been a while since I did it, but it was worth it to hire a pro for the inside if it isn't in good shape. The DIY kits weren't great (15ish years ago).

The outside is easier to do - just get the right paint.

Be better off leaving it alone. Many people might prefer a non-reglazed one.

Any suggestions for reglazers of cast iron tubs in DC? I know posters will try to talk me into buying a new tub. This is for the purposes of selling our unit. Thanks!