David,
calling commit is essential, but IBO starts transactions whenever
neccessary so you don't have to bother about StartTransaction (I think that
when you use StartTransaction IBO leaves more of the work to you and might
not do some of its default behaviour, but I'm not quite sure) - I just
never bother to call StartTransaction and haven't run into trouble yet.

Your properties seems just fine - I might have used tiCommitted rather than
tiConcurrency, but I don't think it matters. So from here, I'll leave you
to the experts, I can be of no further help.

Set