Infantry of World War II and Big Tanks

I better eat my words on general or beginner sites, because right now that's what I need, or you fine people could help me.
I'm basically doing some preliminary research on the major types of infantry, tanks and aircraft used in World War II. Aircraft is covered just by memory or scanning through some of my books. Being unfamiliar with the terrestrial details of World War II, I found a good site as far as detailed armour specs go, and checked out a book from the library to acquaint myself with the major types. Infantry however has proved to be one tough cookie. At first thought I took this to be the easier of the three groups, but so far all I could think of is standard infantry and bazooka teams. So questions are as follows:

- What are the standard infantry types of World War II?
- What are some unique types of infantry? (like the American flamethrower, I think)
- Were there any tanks in World War II, even concept or experimental versions, that were multi-turreted?