i'm not an expert but i'll try answer your questions..
lots of people have discussed accommodation in the following threads:
accommodation
Which is the best Manchester Accomodation??
so maybe have a look at them..
there is plenty of information in previous threads if you access it..
1. i think the poll answers this question but it's a personal thing..
would you prefer to have to cook yourself or have someone do it for you? be able to eat when you want or have set times? get to choose what you eat or get what you're given? only you can really answer that..
2.there was an accommodation day where you could look round everything but as far as i'm aware not everybody had there offers then..
i think it has been mentioned previously that if you ring up the accommodation office you might be able to arrange your own tour (but don't quote me on that) i'd recommend this if at all possible as places that look nice on the internet aren't the same in reality..
3.and yes the deadline is 31st august. they start allocating accommodation after you offer becomes unconditional which will be results day for school leavers or after CRB checks or something..
so it is probably best to apply asap..
and there is no first come first serve basis..
you may also be sent information on accommodation separate from the offer pack thing (i was at least)
which halls are best have been debated in the threads i have given at the top by people who know more than i do..
like i said look around the site and you will find all the information you are looking for..