lc, apart from re-searching and asking loads of questions on here, you can also phone one of the big companies or look into going to a road show, i went to the FWC one the other week and i got some invaluable info from there and went on to buy a backpack and this has given me a good insight into the WFP.
The other option i to ask on her for someone local who does WFP and offer your services free of charge for the day so they can show you everything you need to know.
i am now really getting into the WFP but working from a backpack can be slightly frustrating because of the small capacity, i know when i get a van i will be looking at about a 400L tank and that will do me for a full days work no problem