Great. Glad you got it out and the threads were ok. Don't be too upset, this is something that has happened to just about everybody at one time or another that works on mechanical things. Most of the time things go as planned, sometimes they go terribly wrong. I have had easy outs break off in a stuck bolt, making it impossible to drill the bolt out. I have had to replace a couple of motorcycle engine heads because the header stud broke off flush, and I damaged the head trying to get it out. It happens. Glad it worked for you. I would suggest replacing that washer at every oil change. It is soft aluminum, and it "squishes" when you tighten the oil drain bolt. The next time you change the oil, it will already be squished. They are only $1.99 each. Something else I've done with a number of drain plugs on both bikes and cars is to drill a small hole through the head of the bolt from side to side, and safety wire it in place. That physically holds the plug in place, and it no longer depends on it being really tight.
I am curious where you got that heat gun. I paid around $20 for mine at Home Depot. It gets hot enough to burn paint off. As for all the stuff you bought trying to get that bolt out, it may have been expensive, but you have now either started a tool collection, or added to your existing collection. One cannot have to many tools. I would be completely lost without my Dremel. It is probably the most used power tool I have.