Newbie for DTT

If someone can point me in the right direction.

I picked up a 2nd hand DTT receiver at a bootfair at the weekend it
works as I can get Channel five on it but cannot get any other channels,
(I know it's weird but that's the way of things), even though they are
in the listings. Every time I try add or store channels it finds no
channels.

What I would like to know is:-

a) I live in Biddenden in Kent and the postcode checker says yes to DTT,
C5 is working on an antiference Set Top Aerial, I believe I need to
point at Dover but I would like to know the Channel Numbers so I can
test the signal strength. I believe there is a site that gives the
channel numbers for the multiplexes by transmitter.

b) The dtt box is one of the old Pace Ondigital boxes with the card slot
and I have the remote as well. I wondered if there was somewhere where I
could download the manual if I input in the model no. I paid £15 quid
and C5 is working but I would like to get all the freeview channels to
work and maybe subscribe to Top Up TV if the box is not faulty.

c)Finally are there software updates being sent for the older DTT boxes,
if so where might I find a listing that would match this box.

Thanks in advance