Those bullets all look good.
For the water changes I'd do one every other day along with the redosing of meds.
Okay, for the RO water you can't use straight up RO water because it lacks necessary electrolytes for fish. Not all conditioners will detoxify heavy metals but some will. I'd get Prime for this reason. You can do 50% RO and 50% tap for the time being if the tap is that bad. Usually if you were doing stuff like this I'd suggest testing ph, gh and kh and all sorts of jazz and make sure everything looks good but you're there until the 2nd and this is temporary so just mix 50/50 and use Prime. This is generally very safe.
Also changing his water source may be very stressful on him. Make sure you acclimate him VERY carefully and slowly to these changes. There may be huge ph and gh jumps and all sorts of things that could shock him.
I don't think warming things up in the microwave is going to work.. it will get hot too quickly and you have little control over it. You could ask your parents to get a new 5 gallon bright orange bucket from home depot: http://www.homedepot.com/buy/homer-b...l#.UNqinm-6bOs
Or something like that and add an extra heater and mix the water up there.
Honestly I struggled with how to do water changes with aged water and 10 degree temp differences and finally I only have 3 solutions that I like
1) Premix and preheat with a separate bucket/heater
2) Float fish A in a cup in fish Bs water during the change (maybe not the best idea because you're sharing tank germs, but it's certainly the easiest one)
3) Have two identical tank setups so you can do your 100% water change in one, get it up to temp, then move.
Third is pretty impractical but I've done all of these at one point or another. I've also used a heavy duty space heater and aimed it at a 1 gallon glass bowl until the thermometer reads about 2 degrees below where I want it, then quickly take it away, wait until temps stabilize (ususally rose about 2 degrees) and go from there.. IDK there are all sorts of ways of being creative.
I wouldn't use anything that has ever touched soap but some people do and it's okay. Just make sure it's rinsed *extremely* well and nothing porous - so no plastic. Glass/pyrex is prob okay if you're careful enough.