BV, first off Junket is very weak, if you HAVE to use it, use 5 times the amount. But if you really want to make cheese you have to get real rennet, and yes your rennet from the kit is definatley bad by now. Next time put it in the frig (not freezer). And while you're at it get some cultures. Making cultures at home is another hobby all together, but some DVI as it's just easier and you know it's going to work. DVI, freeze dried and so on cultures shold be stored in the freezer. As far as heating you can use direct heat but have to stir constantly, but it's not recommended, buy a bigger pot for a double boiler. Check goodwill or thrift stores. Seems as though your headed in the right direction and should have a good cheese next time.