On the subject of chain elongation, I've learned that chains don't "stretch" ... they wear on the bearing surfaces, effectively making the chain longer due to the thinner bearings.
As far as torque is concerned, you should at least get a torque wrench for those fasteners that require a torque value, such as crank bolts, disc rotor bolts, etc. They are expensive, but if you get a nice one (such as a Snap-On 1/4-inch dr), they're guaranteed for life and can be calibrated. You will never need to buy a replacement.
In any case, I suggest going through the Barnett's manuals before you do anything, so you can learn to troubleshoot problems correctly.
Post a pic of your ride!
