The kitchen faucet is a very common type and you just need a set screw of the proper diameter and length to replace the one that's gone missing. Take the handle to a home center's plumbing repair aisle, or to a plumbing supply house, and you should be able to get one. You may want to soak the lever in some vinegar first, to clear the calcification so it's easier to test and install the replacement.
For the bathroom faucet, a replacement lever will be harder to find but it's possible you might find something workable. Worst case you can just leave some vise grips clamped on there: