notch welding questions

[shifty]

i have had my notch bolted in and tack-welded for a couple of weeks now and will probably get time to finish out all of my welds today. i had a couple of questions for you guys, though - actually, several questions -

i have a Lincoln 175HD that i'm using with 75/25 gas and .025 L-56 wire. i got a lot of my practice in by welding up trellises using 3/4" steel tube and 3/8" square rod. i've noticed that when i'm welding, for the first 1-3 seconds, i usually don't get a good 'crackle', but pops and sputters. after that 1-3 seconds, i get my good crackle and can run a decent bead, but by then, i've piled up so much of a puddle it's silly.

so, here are some questions i have:

-> is .025 wire w/gas suited for welding in my frame notch?

-> should i use a pattern when welding this up, like weld an inch, skip and inch, weld an inch, skip, then fill in the empty spaces after?

-> how will i know if my wire feed speed is sufficient? like, how do i know if my wire speed is too fast or too slow?

-> i assume i should run at power level "E" (A-E are options) for this thick of metal, right?

-> how do you really know whether to use A, B, C, D and E without looking at the cheat sheet on your welder?

finally - why is it that i can't seem to just strike off with a good crackle from the get-go?

i gotta make a run to the nursery to get some trees, was hoping to be all welded up by end of day today. any answers are appreciated, and any other advice you think might be helpful for my noobishness at welding is appreciated. i guess we all learn somehow