Not the answer to your question but an observation: I have found that buying rail tickets in (some) European countries incurs VAT while buying outside those countries can be VAT-free. (This doesn't apply for example in the UK where there is no VAT on most travel.) I'm happy buying online so would look at that to see whether VAT is payable.

Consider the link on the Ryanair website for the bus from Venice to TSF? It's http://www.shuttledirect.com/en/airport/TSF/Ryanair (I haven't used this - we used the separate bus Mestre-TSF.)