Try and keep about 1/4" stickout of the wire..may need to use more flow of gas..bring up the heat..that should help control the spatter..Still gonna have some tho..
Take a flat plate and get comfy and run bead all afternoon until you are getting a good consistent result..good beads do not need to be ground just wire brushed is all..When the local tech school trains welders those guys spend all day every day in the welding booth till they get it right...
Body sheet metal is a different thing as we do grind those welds to get a smooth surface for paint..
Here is a link with some pics of good and bad bead..
Hope this helps a bit..