MIG brazing particulars

Can only answer #3. I always liked to use an oversized liner, as they don't fill up with crud as fast. As long as the proper tip and drive rollers are used, I don't see a difference. I went through a lot of liners, and always put in .045", and it lasted longer than the liner that matched the diameter of the wire. I don't think they really wear out, as I never dissected one. I think they just get full of small steel particles from the surface of the wire.
The Lincoln site has a help question section that I have used, and find them prompt and actually helpful.
YMMV, and all that.
Steve

Greetings Bob, I have a Lincoln SP125+. I love the little machine. It will weld with .023 silicon bronze wire. At least I think it's .023 wire. The smallest available wire is what I use. The little welder is just powerful enough to use this wire. On heavy material pre-heat is necessary. I have welded silicon bronze sheet and castings and brazed steel sheet with the SP125+. Unfortunately argon must be used. C25 won't work. I learned to use argon but tried one day using C25 and the welds were crappy. Good thing I was only trying on scrap material. I have been thinking of getting a CO2 bottle because it is so much cheaper than C25. I have an extra regulator and flow meter. The plan is to make a mixing manifold, mount two cylinders on the weld cart, and use mixed or pure gas when needed or desired. That way I don't use up expensive C25 when welding on the backhoe bucket or my neighbor's exhaust pipe. Eric

Yes with 0.023" wire
No, You have to use pure argon, or better argon / helium mix.
Yes the 0.035" liner is fine, just blow it out with an air nozzle before feeding the bronze wire through it. The teflon liners they sell for aluminum welding are way better.
I came up with a system about 12 years ago to MIG braze stainless deck railings together in 8 foot lengths using hidden welds.
I installed 180 feet of that railing. Worked great.
The arc won't sound normal. It will sound more like a hiss.

Greetings Ernie, It was you who showed me that I could use silicon bronze wire in my little Lincoln. At a one day seminar at DIT. Just so you know that what you taught me that day is still getting used. I have even passed along some of my mig welding knowledge that I learned from you to others. Free of charge though because I can weld lots better than I can teach. Eric

Glad it helped

Great - the best reply is always the one based on personal experience.
weld cart, Good idea! 3 shielding gases from 2 tanks and you don't need to keep an argon tank around for just brazing. In fact, I have a CO2 tank & regulator ... when my C25 needs to be refilled I'll get argon in that & do a mix like you. I assume that the manifold can just be a few bits of plumbing.
Thanks, Bob

Oh ... _stainless_ welding, without the rust! OK, not "welding", but close enough. Assuming the heat of brazing doesn't do something to the SS that makes it rust-able.
Thanks, Bob

Check valves - So you don't inadvertently cross contaminate tanks when one gas runs out early.