What is the 'git' number after this? Is it significant?
Not really, it's just a code to identify the exact revision of the source code that was used to build that version. For releases the version number is enough to identify things.
The host machine said DCP-o-Matic quit unexpectedly.
I'd guess this is probably the root of the problem. If the host dies any servers will give errors if they were trying to communicate with the host at that time.
AS usual, it then ran quickly through the job up to the point where it crashed, then carried on as normal. By re-starting, will I have lost the log, or will it still be there after the job has finished?
The log will still be there. The Apple crash report is probably more useful in this case, although you are probably seeing the known OS X crash bug in 2.9.0.