Every supplier is different, but they tend to call the shots, what did _they_ have to say on several of your questions? Many won't run you a service until you have a building permit, they want you to use enough power to make it worth their while, not just a pole with a couple outlets on it....
With the limited info, typical would be:
200 amp service.
Main breaker out by the transformer. Which is located in a central location to the buildings. The shorter the run of 220v wire to each building, the _better_.
Branch to the house, 200amp or as close as you can get. Can get by with 100 amp, but can be limiting in today's world of tankless water heaters, geothermal heat pumps, etc.
Branch to the out buildings - 100 amp anyhow, closer to 200 amp is smarter. You can branch from one building to the next, or run branches from the central transformer switch to each building, depending on which is shorter wires.
Most folks like to go underground now, I'd sure look into it, when I rewired the REA brought the main lines in underground for only 50 cents a foot...... Sure was a bargin.
Will you want a power backup generator ever, that special switch can be part of that main switch by the transformer, costs a little more, but won't have to redo it at bigger expense later. Good option to consider.
- Oh, breaker box - each building will need it's own. I refer that central box near the transformer, sounds like you are thinking of feeding the house right from the transformer, and wishing to feed off that house box to each building. Can do that too, but it means all power flows through your house, just not a fan of that. But then, I have a farm with 9 wired buildings plus the house..... you wouldn't believe the size of the wire needed to run 200 amp 220v wire 750 feet to the far buildings....
Anyhow, each building has it's own breaker box, and you'll need to run 4 wires to each - hot, hot, nuetral, and ground with the proper grounding bars. Put a big breaker box in the house, you'll end up using it all there. Really, people aren't joking when they say that.
My farm was wired with a 60 amp service for the whole farm - so to those who say 200 or 100 is overkill, yea I know can get by with less, but it's not the way to do it now a days. 200 amp service, and don't go less than 100 amp wire to any of the buildings, 200 amp all throughout is smarter so if you build a 3rd building, you can branch on to the next new building.... I spent $11,000 getting my poor overhead 60 amp wiring up to a good 200 amp service some years ago. Worth it. You'll get by a lot cheaper than that.
--->PAul