Does anyone know how to find the steerer tube length on a Camber?

I'm considering getting a used Talas to replace my Recon TK on my (120mm) Camber. Hoping for some opinions. Looking at some used 2007/2008s with 100/120/140mm adjustable travel.

120mm is about ideal for my local trails. I plan on doing some XC racing in the spring so would like the option to go down to 100mm, as well. I'll mostly be competing with myself, and don't expect to move above cat3 anytime soon, so this isn't meant to be a "racing fork" per se. My front wheel already lifts up a bit on some steeper climbs, so just would like 100mm to help with that.

There are a couple trails where 140mm would be welcome, and I ride in the Shenandoah Valley when I visit family in VA... longer travel would be nice there, too.

So it seems like this is an ideal fork for what I'm looking for, but a few questions if you don't mind:

1) What are the implications on warranty running a frame designed for 120mm at either 100mm or 140mm in the front?

2) 2007 Talas steerer tube is 9 1/2", 2008 is 7 15/16". Any issues with either? This is one area I'm having trouble understanding. Recon steerer tube length isn't listed on either Spesh site nor SRAM.

3) I plan to eventually put a RP23 on the rear. This would presumably still be at 120mm. Am I correct that the difference in front and rear travel wouldn't be a big deal if both are set correctly?

Thanks for any info.