I'm buying a 6 year old house, elec water heater in attic, if heater starts to leak, is there normally a drain to take the water away to prevent damage to the house or contents?

Okay. My hot water is slow in the tub. Pressure seems fine in the bathroom sink and kitchen. Below is a picture of the current setup. I'm a fair-to-middlin handyman and have done several plumbing projects in the past (complete toilet repair/replacement and adding a whole house water filter to the main water line). So I'm not afraid of the tasks ahead, but must work quickly and with confidence... I'm hoping that the problem lies in the mess shown or even just the seats of the valves. I think it would be better to replace the current arrangement (as shown) with a single set of knobs and shower diverter. I'm in the middle of re-tiling the bath (not shown) so it's no problem for whatever may be ahead. Would this task be difficult? I know that's relative... so let's ask it this way... With the galvanized risers, what kind of problems am I going to face with the new piping (poss. copper?) and joining the two types of metal. I'm assumming rethreading the galvanized pipe is not practical. A future project is to add a second shower head to the existing bath. I would like to tackle this as part of the current project and no how-to has described such an addition. Any detailed suggestions/directions would be greatly appreciated. Thanks! Great forum! Love the UBB. Tim