this is only a personal opinion so here goes
modern vans are as easy if not easier to drive than a car the elevated driving position is a real bonus. height-width and length are the main factors to take into account along with the all important overhang the distance from rear axle to rear of vehicle ive seen many a car swiped as the van/lorry turns sharply
as for the mirrors its more a case of what you feel comfortable with you will always have a blind spot unless you make it look like a vespa the thing i find is narrow the blind spot as much as possible and try to keep it on your side if poss much easier to look out your window than the passengers
not too sure on the rules for vans but i think you will need to keep some kind of record of driving/load/unloading/breaks im sure it will come under the EU working time directive
on another point ignorance is no defence in the eyes of the law so whilst you are driving it YOU will be held responsible for the following
1.Overloading of the vehicle even if you didnt load it
2.General roadworhiness of vehicle ie tyres/lights/bits hanging off anything that you would notice on your own car
3.You will NOT be held liable for things that you would not reasonable be able to detect ie cracks in chassis rust holes underneath cracked discs etc
4.Make a list of who your firm uses for breakdowns/tyres etc with numbers lot quicker for you to phone and sort it cos you know where you are
One final piece of advice is to have a play with it in your yard/carpark get yourself used to how it handles and move mirrors around until you are happy see if you can find something soft like a hedge/bush and try reversing up to it without hitting it--get out and see how far away you are from it (or in it

) to get used to the length
And you will be fine cos its just common sense and you showed you have that by asking questions before you start have fun and keep a little black book of burgerbars/snack vans most essential for that quiet snooze
Colin