May 17, 2010
How do you identify which leak you are using and if not 2.1v3 is it recommended to redo the leak to v3?
The easiest way is to look at Settings > About Phone > Software information if the information matches that of the OTA or LV3 then that is what you have. You can find that information in the 2.1 sticky at the top of the forum. If what you have does not match then you can flash LV3 to your phone and be up-to-date. If you already have it, flashing again won't hurt anything though.
By looking at the Software Info.

I'm not sure about leaks 1 & 2 but here is the info for leak 3:

Firmware - 2.1
Baseband -
Kernel - 2.6.29-8a03cb9a
Build # - 2.36.605.1 CL165907 release-keys
Software # - 2.36.605.1

And yes you can reflash your phone as many times as you want.