As to the air and naval bases you can print some simple symbols, there are lots of those on this forum. The rules are similar… you may also leave those out of the game. Also, some cards mention tactical bombers… I got them from www.historicalboardgaming.com
Air bases allow +1 movement during noncombat phase, allow interceptor rules for fighters and on islands allow the defense of adjacent Sea Zones.
Naval Bases allow +1 movement during noncombat phase and repair of battleships.
Both can be damaged and destroyed during strategic bombing raids but both have AA defense. Rolls of 3, 4 or 5 damage the base, a 6 or more destroys it. The damage is not cumulative, after a bombing raid the base is either operational or damaged or destroyed, no chips here, just turn on the side to show a damaged base.
The decision on the number of National advantages is up to you and the group. If you intend to play with Free French rules you need at least to use one card - Liberation of France. The Chinese must also play with one that already comes with the game - Flying Tigers. 6 cards per major power is the maximum…more than that and you will probably forget some advantages. Each player may draw randomly or choose any decided number of cards or you might just give more experienced players less advantages or try to balace the game allowing the Axis or Allies to have more or less advantages. The number of cards is the same till the end of the game.
Some advantages seem to be major advantages and others minors… you may seek to balance that also allowing only 1, 2 or 3 major advantages per player.