Hanging drywall can be a big chore. Make it easier on yourself by using screws. Screws have much better holding power than nails and can be faster to install through the use of a drill. They can also be counter sunk making mudding easier for a finished look.
Your shower’s water pressure could be affected by a variety of things. Its location in your house could be affecting your shower’s water pressure as bathrooms on the second or even third floor often have lower water pressure. Water pressure is also affected by chemicals that are used to make your water soft as these chemicals serve to lower it.