[Spridgets] Wheel studs.....buy new, or remove and retain?

[derf]

I've done both, removed/reinstalled and installed new.  New is always
better than used, if you can find quality new parts and wait for them
to arrive.
I usually seat them in a press but I have used a spare lug nut and
washer to seat the studs.  I would not just rely on torquing the
wheels on to seat the studs.
To remove them without damage use a press with a piece of brass on the
top of the stud or hammer them out with a brass rod or such and ball
peen hammer.
Wear safety glasses, handle all equipment properly, use jack stands, ets.