Do I need bolts and nuts to install these clamps?

Yes. The kit includes the clamps only — you'll need to source appropriate bolts, nuts, and washers separately based on your mounting surface and preference. Standard automotive hardware from any fastener supplier works fine.

Can I use these on a temporary patch or do they need to be welded?

These are designed to work without welding. The lap joint seats directly around your tubing, and the bolted connection holds it tight. They work for temporary fixes, custom builds, or permanent non-welded installations.

Will stainless steel clamps handle the heat from my exhaust system?

Stainless steel has solid heat tolerance for exhaust applications. These clamps won't corrode from temperature cycling or moisture exposure the way mild steel would, but monitor bolt tension after your first few drives — vibration can loosen fasteners slightly.