my kitchen sink straight pipe leading to the s pipe leaks when running water. Tightening the collar does not help. I live in a 20+ mobile home. Would plumbers cement fix this leak. I cannot afford a plumber at this junction. Want to fix this problem myself

I have a typical exterior frost free hose bibb. Now, I understand that frost free does not mean freeze proof and it has never frozen up before but I still worry that it might in the future. The piping goes from the hose bibb, into the house about 2 ", turns 90*, and after about a 4' length of pipe, feeds the washer.(looking at the pipe layout backwards, so to speak) Would it make sense to install a stop and waste valve, or something, even though the piping length that it would have to go in (between the washer and bibb) is along, and maybe 2" away from, an exterior wall and in that way, allow me to close the valve during the winter and drain the outermost section? If so, can I install the valve with compression fittings, as I'd be afraid of burning down the house working that close to the framing with a torch. Thanks, Dan