Hi Scott,

We went on a similar connection from ABZ to TFS last year - KLM to AMS then Transavia, and went through the same grief as you trying to figure out the costs.

As it turned out:
Carry-on was exactly the same as allowed on KLM and the Transavia staff were very nice about it.

I don't know why they (KLM/Transavia) don't make the policies more transparent upfront.

As for hold luggage, my KLM FB status allowance was honoured by Transavia, though that wasn't at all clear when booking.