Zippy,
The three squadrons of the AVG started 1942 with all P-40 B/C (many without the wing-guns), but started to get P-40 E during late March to early April 1942. As they had bomb-racks, the E models tended to get used for ground-attack, with the B/Cs providing escort. They never received any other aircraft types. The first USAAF squadrons operating in support of the Chinese out of Assam, India were equipped with P-40 and A-36 Apache (the dive-bomber relative of the Mustang).
I did an early-war Burma campaign with my Minions some years ago. Have a look at this thread on The Other Place, which includes a full order of battle for the early part of the air war over Burma (at 1:2 ratio - I scaled the numbers down by half to make it more playable):
http://theminiaturespage.com/boards/msg.mv?id=370152Re Japanese opposition to the AVG in Burma: It was all IJA, so no Zeroes, as they were purely an IJN aircraft. While some Oscars/Hayabusa (of the 64th Sentai) did turn up over Rangoon during the Christmas raids of 1941, they were immediately then sent off to Malaya and didn't come back to Burma until the 64th Sentai returned in mid-March 1942. The vast majority of IJA fighters over Burma were Nates; chiefly belonging to the 50th Sentai & 77th Sentai, but joined during March 1942 by more Nates from the 1st Sentai and 11th Sentai, as well as the Oscars of the 64th Sentai. There was also the curious 47th Independent Chutai, which flew half a dozen pre-production Tojo/Shoki interceptors.
Bombers were predominantly Sallys, with some Lliys, as well as Babs recce birds fitted as light bombers (mistakenly listed as Anns on my orbat), joined later in the campaign by more Sallys and some Sally IIs.