Do It Yourself Help-Home Projects

[Kimbo]

There's a lot of talent here. I was hoping we could help each other with home project questions.

I happen to have a few home projects going on right now and would like to ask some help of someone who knows plumbing.

This is my dilema:

Kitchen - good cold water pressure and poor hot water pressure
Bathtub - has poor hot and cold water pressure
Bathroom - sink has great hot and cold water pressure.

I have replaced the kitchen and bathroom sinks within the past year and I am hesitant to get to involved with my plumbing because it is old galvanized pipe--where is the problem at, just the screens or is it indicitive of an issue with the hot water heater (which is about 15 y/o)?

I've been warned about touching the galvanized pipes..is it true they are hell to work with?

Where is the shut off valve for the tub and how hard is it to replace the whole unit, shower and faucets in the tub. I have the tile slated to be torn down and replaced in Jan so opening the wall is no big deal. I'm just afraid my hot water pressure is not going to make it until then.

Also I have bit of rot in front of the tub--is there a way I can guage how bad the rot is without lifting the tub?

Help.