The heat and speed you need to use will come with practice. You'll look at what you want to weld and at least know approximately what settings to start at.
Practice welding two pieaces together, butt welded, overlapped and perpendicular. Start with pieces that are the same size and then different thicknesses. Try to break them apart, to see iff you're getting good penetration and where the failure occurs. If they don't easily break apart cut them perpendicular to the weld to see how the penetration is.
Try different techniques like a fillet weld and then the same configuration but chamfer the edges.
If you're like me, and don't weld very often, it's a good idea to run a couple of practice beads to check out yourself and the equipment.
Some of your beads look pretty good, for just starting.
