1 – Probably, lets look at it. The AC units likely draw about 1500 watts each. So 2X1500=3000. So assuming the power draw is correct and the generators are designed to be parallel connected, you should have no problems. Now, if you connect the generators to the AC in on the Multi, then you have 4000 + 2500 watts in power assist (you will never get 3K, so use 2500 for your calcs) = 6500 watts. Should be more than for 2 AC units. Quite possibly you could run one generator and get away with it but your batteries won’t last long. However, you really should find the specs for your units and do the math yourself. The compressor starting may be momentarily higher watts, so leave some headroom there, the power assist should be more than enough though. Soft starts on the AC units will help as well. We occasionally camp at 30 amp 120 volt campsites. 30 amps is 3600 watts, close to the output of your generators. We have a 3K Quattro in a RV with 2 X rooftop units. We can run both AC units and a few other electrical devices, coffee maker, microwave, etc at the same time with no issues.
2 – You need to set the correct input amps on the MP. Once the load exceeds the input amps the power assist will come into play. You can set the input amps several ways, but the easiest is to install a Digital Multi Control, then it’s quick and easy to set the dial for the proper amps.
3 – If you are connecting the shore power cable plugged into the generator(s) you will not need a transfer switch. You are basically using the generator to provide shore power, so no extra switching is required. A transfer switch is typically used if you have a built in generator to switch between shore and generator. And yes the Multi has a “transfer switch” but not the kind you are thinking. The Multi transfer switch switches between inverter and shore power, not generator/shore. You need a Quattro for that.
You didn’t ask but if you don’t have a Cerbo or GX device, you should think about getting one. With a Victron MPPT it will allow everything to work together, especially if you have Victron or Victron compatible batteries.