Briar12, if you serving tight and tying off tight, #4 nylon will work just fine. If you like to spend money, braided is fine, too, but not necessary!
If you whip, reverse wind back thru the loop on the end tie-off, about 20 wraps, should be no problems!
As for what direction, Bull..... If you tie off good and tight, does not make a difference! Your are not rotating the string off your fingers, during release to matter!
If so, all the factory strings, in the '60s thru the '80s that were served in one diretion, were not right, Right? Trust me, and good shootin,
Steve