Using a plastic drum?

[bht9665]

I have been making 5 gal batches and putting them in my carboys. I am using a corn and barley recipe. I found a 35 gal plastic drum in town the other day and cut the top out. I was cooking the corn and barley for my 5 gal carboys but it would be easier if I could make one big batch. This is where I need some help. I know a lot of people use 50 gal drums for fermentation. How do you cook the corn for a recipe this big? How do you cover the top of the barrel? I was thinking that I could put some Saran Wrap on the top then punch pin holes in it. How much yeast do you use in a batch this big? Thanks for any help.