The JB Weld thing....we are talking about bedding the rail to the action. Some use JB Weld, Marine Tex, Devcon, or ACCU Gel from Brownells. Bedding the stock and/or the rail assures a repeatable nest to compensate for the tolerance variation on the 700 action.
On the rifle below, I have a 20 MOA rail with a NF NXS mounted. The 20 MOA rail assures that when dialing elevation for long range targets, you don't run out of adjustment. This rifle is zeroed @ 100yds, and shoots .5 MOA at ranges from 100 to 800 all day long.
If you choose a zero MOA rail, then you will rely on the available elevation adjustment in the particular optic you choose. This only matters if you range with the reticle and "dial" your scope. If you use holdover, it doesn't matter what MOA rail you use.
Is it necessary to bed the rail? IMHO yes, that is.... if you want precision in your long range shooting. If you are OK with 1-2 MOA, then it probably wont matter