Yes that is the email, they should be able to provide information on your cabinet.
As for provider you can either go with one of the big isp's now and upgrade to FTTC or choose a smaller isp and take their fttc service.
Some isp's do offer monthly contacts if you dont want to be tied down to any isp before FTTC becomes available.
They don't always respond to e-mail regarding FFTC cabs rfs dates ect, I know a few people who haven't as yet had any response from them,
IMO Your exchange starting to accept orders is only 1 part of it ,the other part which is equally important is your FTTC cab accepting orders, both in a lot of cases don't happen at the same time, unless you A, live in an area that BT think will provide a high take up.(most affluent areas) or B live within an area that already has a VM cable broadband service , And i would bet that both those type of areas only get a low take up , Which is what has so far been the case in one surrounding area to me served by a different smaller exchange , BT planning leaves much to be desired in some areas
And yes they do connect power to new cabs ,as part of the installation process, they didn't at first, and probably don't in all areas as yet,as quite possibly they only have a small number of engineers trained do do this work, carillion carry out this work on openreaches behalf