I have A&A1942 and it comes with 2 AC for USSR. You are not missing pieces. There is also a thread in this forum for a larger revamped A&A1942 map made by IL.
Air units are the only units that cannot non-combat move into a territory taken that turn. You can “reinforce” territories that were captured the same turn with any land units you want (that can reach of course), including AA guns.
Yes. However, in this particular example there would be no need for them to do so, since with the bomber unable to hit them any longer the battle would be effectively over.