Bosch lists a segmented blade HM-RIFF that it says will cut grooves in porous cement, small cutouts in soft wall tile. I guess four grooves would make a cutout. A lot will depend on the thickness of the brick,.Are you looking to cut thru a brick veneer or the entire thickness of a conventional redbrick? I would try to get a similar material to practice or trial cut. The width of the blade looks a little wide to cut the short sides. You may be able to make a series of long cuts then chip out the segments.
Successful soldering (you're not welding, and you have the wrong torch if you want to weld) requires that the work be physically clean (scrub it) and chemically clean (flux) - you need a very aggressive flux for stainless, because the reason it IS "stainless" is that it forms a strong oxide layer which protects it from most corrosion. Kester is not going to regard stainless as electrical work, for one thing, so don't bark up that tree too long.
With thin stainless, the other problem you almost certainly have (stainless conducts heat poorly, which makes it very easy to overheat) is overheating the work - once work has been overheated, you have to return to physically cleaning it and refluxing before you have a hope in heck of getting solder on it. You also need to stay out of the "oxidizing cone" of the torch flame - ideally, switch to an oxy-acetlyene torch, make the flame rich, and only use the feather - but you can get there with propane if you're careful. The thickness of the solder does not matter much - you heat the wires, and melt the solder on the wires - don't heat the solder.
You could also move up to brazing, which is a process similar to soldering but at higher temperatures, using different filler metals. When most folks refer to silver soldering, what they actually mean is silver brazing (the rod has some silver, but not a huge amount.) The solder you linked to is a low-temperature solder that has silver in it, from the "lead free" change in "soft solders."
What this is doing on a DIY home improvement site is another question. High voltage electrical projects are not exactly the bread and butter of DIY. Another approach in a lab setting would be to do the whole job in a glovebox full of nitrogen or argon. You could also TIG weld it, if you were good at TIG welding. Spot welding might be another approach, but that will also work better on stainless in an oxygen-free atmosphere (glovebox, etc.)
Best Answer
The fitting brush will work if you use it with the proper sized copper pipes. When I say it will work I refer to cleaning oxidation off pipe and fittings. You should expect reasonable results for both the outside of the pipe using the holes in the tool and for inside of fittings using the brush.
This brush will not work well for removing burrs on the end of cut pipe. For that you need some type of reamer tool for the inside of the pipe and a file for the outside edges if you are cutting with a saw (a rotary pipe cutter will not leave a burr on the outside that would be of any note).
In the end, sans the tools of various types, there is still emery paper to clean up pipes and fittings too. Steel wool works too but may leave more debris inside pipes and fittings.