The way I see it is this:
A. If the rules do not specifically ban it, then it’s legal.  
Bidding is a house rule, it’s not to be found in the rule books, or I have yet to see it as even an optional rule.  For perspective, TECH is optional and is mentioned in the rule book, so it’s not a house rule even if implemented in a game.
B. The rules already put non-Chinese units on the board for China and allow China to use them as if they owned them.  Allowing them to do the same for other pieces does not feel like much of a stretch, just annoying because now Veqyrn may have to go back into TripleA and edit it so these pieces can be added. lol. (Sorry, it’s literally the most annoying thing I can think of, and even that is tenuous because how many people are going to bid Strategic Bombers or Tanks for China?)
C.  The spirit of the bidding rule is to allow the player to make up for the fact that s/he feels his/her side cannot win with what it starts with.  If they think a tactical bomber for China (and 11 IPC might not be too much of a stretch to see in a bid) is what they need to contain Japan long enough for America to come in, then let them.  If you don’t want to see that happen, counter bid 9 IPC and bar the option from even being on the table.  Likewise, 1 armored unit is probably not optimal for China, it’s too hard to both use and protect at the same time, though it might come in handy at times as a piece that can stay in newly conquered territories, then again, the planes can retreat from forward positions to safe areas so they both have some merits.  Personally, I think Artillery is better, but that’s me.
D.  China’s units are still restricted to Chinese controllable territories which means no matter what the bid is, you’re not going to see Chinese Aircraft Carriers - I don’t care if you give them 100 IPC worth of units to put on the table! Â
As for a D-Day rule, it should have been floated in House Rules instead of a league discussion thread.  The idea, in a nutshell, was once, per game, the British and Americans in the European theater could have a joint attack on: Normandy and Holland or either one if they didn’t want to hit both.  That would mean shared transports, shore bombardments and air cover.  I still think it’s a good rule, but it’s a house rule for the oblivion of other house rules. lol.  IF we ever end up with a G40 Enhanced then we may see it come back.