I'm partway through my first venture into HOI3 as Germany, and I'm looking for some pointers

The year is mid 1838

Current situation
"annexed" France (Vichy France CB)
Conquered lowlands
Conquered Denmark
Conquered Poland
Annexed Czechoslovakia
Conquered Switzerland

Where to go from here?
Should I try to invade the UK, or move on Russia?

I was thiking about taking the Baltic states, but I heard Russsia will DOW you if you do that.
I didn't get Memel from Lithuania though, and have claims on it
Another possible target would be Hungary in my mind

Some random question I had popping up:
How do I effictively intercept the UK's bombers?
I only have 4 interceptors atm, but I'm building more

How do I efficetively use bombers?

What are good places to send my Uboats to raid convoys?
Currently I have them in the strait and the entrance to the Ireland/UK strait

Is it normal for it to take over a year to produce a single plane/sub/tank?

I'm also running out of useful research projects, I researched nearly everything that is 1838, except ships, militia, artillery and cavalry