Attacking Pearl is not terrible. In my experience about half of the Axis players attack Pearl Harbor. Maybe more than half of them. However some top level players do not do this attack. I for one prefer to not do it for many reasons I wont completely cover here. You have already mentioned many of them. The risk of having to expose a Japanese carrier in that sea zone is the main thing I don’t want to happen.
I want all of my initial attacks with Japan to be as efficient as possible. I am trying to prevent Japan losing any ground units to hit backs. So while only attacking the 2 groups of US infantry may not seem like high value compared to other targets, doing so with decisive attacks that are somewhat overkill is what I want to do.
Often there are UK ships in range somewhere around here to consider attacking as well. I prioritize killing UK ships with Japan over US ships because of the turn order.
The main goal is for Japan to finish round one with zero casualties or as close to that as possible.
The other set up I did not mention is 1 infantry 2 fighters in Kwangtung. Many reasons for this as well such as being able to land in Ukraine or West Russia if German can take them round 2 or even Caucus sometimes and then have the fighters land to help them hold that position. If you can safely place a carrier in sea zone 48 (instead of sea zone 60 to protect vs bomber in India) then the fighters in Kwangtung can still reach sea zone 45 from there because of the carriers position.
This is up to you and your goals with Germany round 2. But it is a good place to be. It also denies US or Russia from a quick 2 IPC boost from trading Kwangtung.
You might want these fighters to be in Manchuria for the potential counter attack if Russia does use its fighters to attack Buryatia. This is up to you. Killing those Russian fighters if they did do this I think is well worth it. But you need to consider if anything else might be able to reinforce Yakut with those fighters as well? Is there still an infantry in Okrug that could?
Pearl Harbor attack does help somewhat if you think the opponent is going to do KGF. Its fewer escorts that US gets to start with. I will sometimes do that attack for this purpose. It does stop the sea zone 45 move pre-emptively as well. There are just so many things that can go wrong with this attack.
If you do it I recommend 1 sub 1 cruiser 2 fighters 1 bomber attack. Sometimes referred to as Pearl light as you are not bringing the carrier into the battle as well. When you do this take the first hit on the fighter that does not have enough fuel so that your carrier does not have to catch it. This is part of the long list of things I don’t like about doing the attack. Automatically losing a fighter.
As far as building factories round one with Japan? I never do that. Japan has enough build capacity and expensive things it wants to build in the first few rounds that it does not need another factory until round 3. I prefer that first factory to be India. I go for j3 timing attack on India. I think most if not all players know this attack pretty well by now. But if you don’t I could explain that in further detail.
As far as building a factory with Japan I prefer to build it in East Indies. If there are no UK ships in Indian ocean to threaten it you can even build it round one and still go for India round 3 but you will be 2 attackers short of what you could have if you dont build it. Having it built does give you follow up attack options and many other options to use production there for taking Australia and Africa after you take India though. It is nice to have. I just dont really recommend it round one until you see what the Allies are actually up to.