London pedaling

*Left side or right side of the street? *Left.
Are there Bike Lanes? Obligatory? Yes. No.
Red traffic lights? Obligatory? (Wouldn´t like to pay some ticket for this) Yes. Yes.
Bikes on trains? (I know theres a post of this, but is old) Yes, a lot of the time.
Helmet? Yes. Not obligatory but recommended.

Thanks! Any other advice will be welcomed.