watch sum vids on youtube about arc welding i would recomend go in by this rule
if ur metal for instance was 1/4 inch thick use 140amps
and so on
you may have to adjust your aperage depending on metal and weather conditions
as for electrode 6013 are easy to weld but require a longer process of small circle shapes to get a good bead
7016 would be good too but they are a little bit harder to use and are considerably harder hold a steady arc
just play around with your welder a bit it all varies with ur welding skills
kinda. practice first and get a hang of starting the arc. U can either scratch it like a match or tap it. I personally find tapping the electrode to the metal easier.
i can arc weld relatively good so the other day at school we had the amps down real low and it was sorta creating little spots would this work too if the spots were bigger? the tacks would only be in place to get the frame squared up