As for the first post, Billsteins are definitely the way to go. They will stiffen up your ride a bit, but in return you'll get improved handling, less body roll and less bounce after bumps. I have them on my 2000 4Runner and had them on my 97 tacoma and wouldn't go with anything else.
As for the second question, the front shocks can be replaced independently of the coil spring, the springs should really last forever, unless you keep it for a decade or so. The back as stated is an easy switch, except that you can't see the top mounting bolt and have to put a wrench on it and remove it blindly, but it's easy to feel and no big deal. In the front the shock is in the spring so you'll need to remove the whole assembly and compress the spring, once againg easy with the right tools and location to work on it. I had a shop put the shocks on the runner as it was cold out and I had no place to work on it but I did the tacoma w/ a friend and it took us a few hours total.