I don't think ants will hurt the rabbit, but you are usually advised not to let them out of the hutch for a couple of weeks anyway (depending on how old it is)
you can leave the run on paving, it'll be good for keeping the rabbit's claws nice and short but they do need to go on grass as well, easy enough if you have a small easy to move run
yes, you can leave it out in the run and just shut it up at night, as long as it's nice and secure
keep to the same rabbit food to start with. rabbits have very sensitive tummies. you can change to russel rabbit if you want, but do it gradually
they can't have potato, lettuce, rhubarb, evergreen shrubs erm, theres prob more but that's all I can think of atm
you should give them some fresh food every day
I used to feed my rabbit once a day, sometimes give a top up in the evening if he had eaten a lot though.
yes, they need injections. myxamatosis and one other (can't think of name right now) jabs at least once a year- probably twice a year if you are in a rural area and there are wild rabbits around