Advice on handover at dealer

Well, thanks to this site, handbooks and the CC, we've got the right tow car, the insurance, the towing course, have purchased most of the kit needed for the van and probably some kit we don't. Just need the van now  , which we are scheduled to pick up this Friday. Brand new van, zero caravanning experience (yes, I know...)

Undertaking an idle google search of "[name of caravan dealer] reviews" a week ago has left me waking up in cold sweats, though I realise complainers will articulate their feelings more often than happy customers.

What I need to know from you experienced folks is what should I be looking for, or asking, or checking at a handover? I am probably as concerned about what I should be checking for in terms of the construction of the caravan rather perhaps than how to change the toilet waste, but if there are essential features which a novice should ask an explanation for rather than leaving it to working out on site, please say. 

Cheers!