Two different pressure issues in one house Plumbing

I'm trying to identify what these two issues are and if they're easily fixed.

1) At times the pressure seems to be excessively high. For example, I'll turn on the kitchen sink and the water will come shooting out of the faucet (where it's supposed to) and then peter down to a normal pressure. This doesn't always happen, nor is it limited to the kitchen (though I think I see it at the kitchen sink or the water machine on the refrigerator the most). Any ideas? I believe this might be cold water only, but am not positive.

2) Hot water pressure is variable as well, but the other way. It seems to happen most frequently, and most significantly, in the shower closest to the water heater (not sure how the pipes are actually run, but there's only a wall separating them).

The house is about 14 years old, and I'm almost positive that the water heater and the rest of the plumbing are original. It's a quadrant home if that matters.

Any ideas as to what would be causing these seemingly separate issues? Is it likely something that I can fix myself (I'm renting, so it would have to be pretty non-invasive)?

Submitted January 30, 2015 at 11:16PM by superthighheater3000 http://ift.tt/163aaXi Plumbing