Welcome to the forum!
Sometime it takes a few days for the bettas to adjust and ready to eat. He has probably been through a tramautic time and will take a few days to eat. also, for the first two weeks, i would feed my betta, and it seemed as if he never ate. though he must have sometime. Now he is adjusted well and i can watch him eat. So give it more than 2 days...
also, the bubble nest thing, that takes a while as well. Again, he still has to adjust. Some bettas just don't bubble nest, some do. Usually it means they are ready to spawn (is that the word?) and maybe he isn't ready to. also it will probably take at least 2 -3 weeks for him to make a bubble nest at least.
some feed their bettas 2 times a day, some everyother day, i feed mine 1 time a day and occasionally twice a day.
Get him out of the 1 gallon tank asap! look for at least a 2 gallon tank, no matter what is said they do NOT require a filter and a heater. It is nice to have them, and they like them, but the fish won't be unhappy, will make bubble nests and won't die if their tank falls under 80. mine is room temp, about 72-76 degrees and he seems happy and makes bubble nests.
Good luck with him!