Your post is not very clear, but I’ll try to address your questions. From your first question, it sounds as if you are unable to completely turn off the hot water at your bathtub. That probably means your hot faucet needs to be renewed. How to do it depends upon the type of faucet you have. Is it a single handle type, or two handles? Can you identify the brand of your faucet set? Basicily, you will need to turn off the water supply and disassemble the faucet to replace the necessary parts. If you post back with more information, we may be able to give you more specific advise.
About the water pressure problem, you say you don’t have water pressure. Do you mean that no water flows from either hot or cold faucets? Although you say water pressure, most folks are complaining about LOW WATER FLOW, NOT LOW PRESSURE. Can you verify which you mean? Is this a new problem, or have you had this problem for some time? Have you had any plumbing work done on your home recently? You also refer to the drain – there is no correlation between water pressure and the drain system. Please post back with clarifying information.
.
