When replacing carpet, can you re-use the tackless strips?
Certainly, if they're in "decent enough condition". Which means they aren't showing any signs of mold and are still well fastened. And that the 'tacks' will still grab the new carpet properly (I've never seen any so mangled that this was a problem).

Personal advice: whatever reason you took the old carpet out, will be the same reason you'll have to again. -You like oak, Jimmy? I'm a tile guy myself...