No, grinding flush will not affect a good weld, but it needs to be a good weld ;)

Pictures 2 & 3 look much better, a steadier hand will improve it even more.

Ask the local friendly pub landlord, plain Co2 is what you need and they use lots of it, I started out on that and gave him £20 a go, needed to buy the right regulator but it was great for learning on.