How would this interaction work.

Overclocked: During the Combat phase, when you spend a focus token, you may receive 1 stress token to assign 1 focus token to your ship.

Janson:After you perform an attack, you may remove 1 focus, evade, or blue target lock token from the defender.

Janson attacks, Uboat uses focus so that it doesnt get taken agro mechs another would Wes be able to take that freshly Agromech'd focus?

I would say overcloacked R4 would trigger if you spent it defending, but then Wes would trigger and you would lose the focues you got due to his ability triggering after his attack. Per FAQ you are allowed to spend a token you have to defend from his attack, any any left over tokens are then effected.

Yes.

Step 0: U-boat gains a focus token during the activation step.

Step 1: Janson declares that he's attacking the U-boat.

Step 2: The U-boat has the opportunity to spend the focus token on its defense roll. If it does so, it also has the chance to take a stress token and another focus token.

Step 3: You finish resolving the attack, and Janson's ability triggers--including all the decisions you'd need to make, namely which token to discard. So it doesn't matter what happened with the U-boat in the mean time: you look at the tokens it has, and decide whether you'd like to discard one of them.