You should definitely string through body with the L-2500 since the bridge is only held down with two little screws. As many have found out, the bridge rips out of the body if you don't string through the body.
Through body or through bridge has no effect on string tension.
35" scale is longer obviously, which makes the strings higher tension...seems backwards to me though

I guess since the strings are longer, you have to tighten them more to get to the same pitch as 34"
And your G&L is 34"
Best thing you can do to your G&L is to wire up the single coil mod on it. It will kill.