If you go CV line you can only stay with the Hipper and its remodel. Most people sugesst to go the D-land line with your first BO and whore another if you want to get he CV.

What do you mean? You need pilots for a CV... seems obvious to me.

If I were to train another BO for the CV, meaning I have to train my pilots too?

Go for the BB line and train a neutral sailor to make him CV commander. You don't need a skilled BO for CV... and training a second one would be a bloody mess :/

if u have cv line would have to make completly new pilots, and a cv hull is about 2.5 mill give or take, while scharnhorst is 1.2 mill.

The main problem is money, u have to have an hell of an amount of money to do cv.
But u also get alot of money. if you go cv make sure to have 2 bo's one for cv and one for bb.