What is the size of ships compared to the enemy. If you have larger ships, battle generator compensate that by numbers.

Be aware that usually floatplanes are inferior quality so they are slower and your search pattern could be worse.

Is there any way to just invade a neutral (non-major power controlled) area? Playing as the Americans, I have by 1949 conquered much of the known world, but somehow one critical colony has successfully avoided my attention - the Colombian province of Panama. For the Americans, it is a real handicap...

When this happens I cut all funding to stuff that isn't needed immediately. All construction halted. All planes deleted from airbases (not carriers) research cut down to 0 no spies at all and everything mothballed in your home port. It is kinda silly so I agree with the staged demobilisation period...

When you get different options that can increase your budget for costs of increased tension what do you usually choose?

Land base strikes are somewhat a worse quality than carrier strikes as they were not usually as well trained for naval warfare.

They are still usefull and they can disrupt defences or can strike after you carrier strike. But most important for land aicraft is using correct basis close the action.

What do you mean "compare"?

You can open any design you designed but if you would like to see original design of ship I suggest to open it through designing for refit.

You cannot build ship from them. There are intelligence efforts to gain information about enemy ships. You can use this information to shape your navy accordingly, eg. if you find out that rival nation has faster cruiser, you can decide to build even faster one. Practically a lot of ship designs in ...

I would add suggestion about fleet size to be somewhere in the middle, from medium to larger.
Having smaller fleet can be difficult as any mistake can be big mistake and larger fleets can be a little overwhelming.

It depends what year you would like to start: 1890 and 1900: Italy - Suggested as Italy is decent with minimal overseas commitment France - Could be good start too as have large fleet but overseas commitment put another burdern to you. Austria-Hungary -Could be good to but a little lacking over Ital...