Yeast Cake

Can I harvest the yeast from my IPA by taking a big chunk out of the yeast cake and putting it into a mason jar with some beer on it and put it in the fridge? If I pitch that into my next batch will that substitute as my yeast?

Yep, that will work. Personally I rinse yeast, but that’s just what I prefer.

http://billybrew.com/yeast-washing

sure, most people suggest using between 1/3 - 1/2 of the cake assuming the next beer is a similar OG, you can save the rest for futures batches if you want