Pvm/Pvp? For pvm max block isn't really needed, nor is perfect stats, as long as you can wear all of your gear and hit the bps you want to you will be fine. For pvp I'm not sure your gear/level/etc so I can't say where your block lays at so it's hard to suggest remaking or not.
Depends on your gear. Activate holy shield and check what your chance to block is (hover over your defense on the char screen to see actual chance to block). If it's below 75%, add more until it is. If it's 75% either you have just enough or a little extra. Shouldn't be a huge problem if it's for PVM, though.
Yea max block is really easy to get on a pally, and well worth it, but for pvm it doesn't warrent a rebuild on a hammerdin unless you are a perfectionist.