Once again 6120 MAC Certs and Flash.

[Canis-Major]

Way too many questions, but to surmise.. you bought a 6120, so we're talking about a 6120, 2nd hand? Someone is clearly not paying their bill, as in 2nd hand box, you bought it, and your 5100 with mac from a 6120, so you want to put mac from 5100 to 6120, wow, too much scrolling to even get to the point here, like, pmsl... you flashed 6120 with forceware, and are in process of switching isp's.

Sound's like you know what your doing, why ask so many questions when it may just be wait till you swapped isp's and KNOW you have a working line (to start with lol)

Everything else tells me you know enough to get on.