I was roaming the unanswered threads and came across yours. Did you already brew? If yes, well consider what I say for future brews.
Your question regarding the paint strainer; I am not too familiar if that paint straining bag would work. The ones I buy at home depot say nylon. I would give it a go though. Always remember to boil new bags for a couple of minutes before using them, this way you will not introduce that new stuff smell to the wort.
When I did mini mash batches, I would use about 1.5 times more water than my strike water.
62 sounds like a good “ambient temperature” to ferment at, but that is all relative to the fermentation at hand. I notice different yeast produce more heat when they eat. You should really be concerned with the temperature of the beer inside the fermentor. Sometimes that can range from 3 to 10 degrees more than what ambient temperature is. Get a little sticky thermometer from the pet store and slap it on the side of your carboy or bucket.