Brake issue could be bad wheel cyclinder. If you want to get rid of the engine troubles just slap that weber on, the pos stock carb is probanly causing your issues. Forthe oil leak you need to clean ur engine and everything really good then take it for a quick drive and check where oil is coming from. Yiur clutch probably needs adjustment there is a star nut on the cable in the engine bay on the firewall to tighten thr cable.