dodging,
Eye relief is the distance between your eye and the scope, and leveling of the reticles ,is to get the crosshairs level with the rifle bore.
There are lots of fancy, do dads that will help you with the crosshair leveling, it can be done with out them it just takes longer.
The eye relief is important so you don't wind up with a "RED EYEBROW".
This distance is more critical with heavier recoiling rifles. Usually the scope instructions will give you a basic run down on the procedure. You'll adjust the focus to bring the crosshairs nice and crisp, and then with the scope in the rings loose you will slide the scope back and forth with your cheek welded to the stock in the most comfortable spot and bring the picture into focus, no black on the edges etc.
Make sure to use a screw driver and bits designed for gun screws, whether torx ,Allen, or slotted. It will keep the srews from being buggered, the regular old household scew driver is not hollow ground and will cam out of the slots marring the screws or possibly worse you new SPS.
When installing the mounts make sure to clean out the drilled and tapped holes in the rifles receiver, rubbing alcohol, nail polish remover,or brake clean, and a Q-Tip, and get them clean. The same routine with the ring screws clean them and the holes thoroughly, also the saddle portion of the rings where the scope rests.
You can go as far as lapping scope rings,reticle levelers buying a torque wrench for tightening screws and a whole lot farther, but most of this type of expensive gear is for someone who is planning to work on just more than one or two rifles.
If you do the mount youself just take your time and don't get to stressed out , it is a reletive easy job that can be done with the correct tools.
The only thing you may want to farm out is the bore sighting, you might even have the people your buying the rifle from do that after you do the mounting,and I do stress you doing the mounting ,but this also can be done at the range with the proper instruction ,with only a cardboard box and a target and couple rounds of ammo.
The main thing is to have the fun of doing it youself!