Your pool or puddle as it's commonly called is the molten metal following your arc at the end of the rod. At least its supposed to follow it. Never let your puddle get in front of your arc, if you do, then you're not getting good penetration and you're trapping slag into your weld. The puddle should not be too long and pointed at the trailing end, you'd be moving too fast if it was, nor too tight at the arc, then you'd be moving too slow. It should be slightly oval shaped following your ark. So only by practice and experience will you be able to adjust your travel speed and rod angle to produce the correct puddle, which is an excellent indicator as to how well your weld is comming along.Henceforth the skill in welding. Its my experience that if you master this concept, there ain't nuthin' you can't weld!
As for 6011 vs 7018, 6011 will never look as good as 7018 if both are applied properly. 6011 is designed for rusty, dirty metal, and just doesn't look good typically.
Good Luck,
Buffalo