Daz - I used the same hoses, reels & connectors for hot & had no issues at all.
The running cost for gas is about £1 a day I found - and i'm told its about £1.30 a day for immersion heater systems.
Personally, if i was gong hot again I'd go for an immersion heater based system - its cheaper, simpler, quicker to install AND you don't have any worries/insurance hassle about carrying a gas bottle in the van.