I believe your position keeper problem is not a problem at all.
It's not in your periscope view because the P/K is on the TDC, which, from your attack scope in the conning tower, is right beside you. And so, in-game, you have to switch stations to simulate the crewman working the TDC and the captain (yourself), who is giving the target data to the TDC operator. It's to simulate the real-life operations of a U-boat.
As for your radar, maybe incompatible mods. Or maybe it just isn't turned on, or the range setting is wrong.