I agree with your summary (I had not traced the first marriage so that is a welcome addition to my CROOM(E) database) and can add a further item:
-- James Croom died in 1866: Death Registration, Apr-May-June 1866 at Isle of Thanet, Kent, Registry Office.
and some speculation on
William Croom his father who I have not identified but in the database there are two possibles:
1. There is a William CROOME baptised at Calne, Wiltshire, on 12 August 1789. He would be the right age for the father and his father is James, which might add to the probability. Unable to trace further.
2. There is a William CROOME married 16 August 1802 in Kingswood, Gloucestershire with a son James b. 7 Nov. 1815 in Wickwar, Gloucestershire (probably) and bap. 24 December 1815 at the Independent Chapel (i.e., not Church of England), Kingswood, Gloucestershire (or Wiltshire). Unable to trace further.
I hope this is of use (it is not, so far as I know, in my CROOME tree).
Cheers, Gil Croome