just want this project to go right
This is what I think is your biggest problem. Just pick out a suitable 110V welder and chop saw in your price range, and start gluing stuff together.
As I said before, you are going to drive (have driven?) yourself batty trying to get the perfect stand on your first attempt. Give up on the "one size fits all", like your original posts indicated. Pick a batch size/pot, and build to that with just a basic plan. Chalk up the first one as a prototype. Make it out of angle iron if you want. Much cheaper. You will have all of $75 in materials, and you can add or mod it at will.
Even guys that had immaculate plans ended up having to make adjustments on the fly. You can't really plan for EVERYTHING, especially for your first attempt, and more so if you don't have all the parts yet.
It will take about 1 hour of playing around before you can lay a weld bead that will be good enough for a brew stand. It really is that easy. Look at some of the threads of first time welders, and the stands they made. I have yet to find one where the guy wasn't thrilled with playing around with the welder. The hardest part will be keeping the parts squared up when welding, but it won't matter that much if it isn't. Don't bother renting a welder. I can guarantee it will not be cost effective. It will cost more for 2 days than buying a HF welder, and you will not have anything afterwards to make mods with. And, you will still need a chop saw and grinder.
One tip is to make a raised pot stand/grate instead of using the frame rails. Breathing is an issue, and the heat is funneled out the corners only. Something similar to how a commercial stove allows the flame to spread out works better.
Don't rely solely on this thread and your friend who welds as your source of information. There are various threads here on HF welders, higher end welders, and DIY stands. Read and ask questions there, but don't seek perfection or divine enlightenment before jumping in.
The next post to this thread should be a pic of the stand built with your new welder.