The first place I'd look for definitive answers would be Blair's
Silent Victory. One thing I'm pretty sure the Japanese did
not have lots of was huge convoys. IIRC, most of the time they sent stuff along in small batches; they only used massive convoys on a few occasions early war. I'm hesitant to go much further as far as what was "typical" - that changed some as the war went on - or throw out exact numbers because I'm going on memory. But as a ballpark start I would say that most of the time Japanese convoys consisted of less than a dozen ships and probably less than 10, and might include 2-4 small to medium sized freighters and/or tankers, plus an occasional monster. Escorts might number 3 or 4; IIRC the Japanese seemed to like putting 1 escort leading, 1 on either beam, and sometimes 1 in the rear. Of course, if it was a really important convoy there might be five or six escorts....
Hope you get some more precise info (and corrections) from other posters; just thought I'd throw that up as a start.
