I am new to this malarkey having so far gotten away with a small birthday tea for family at home. But DD, who starts school in September, is turning 5 in December and in a moment of madness I have agreed to have the dreaded whole class party! I am 30 weeks pregnant so blame the hormones 
I have booked a venue (community hall)
and an entertainer. She does 45 mins of magic and party games, then 30 minute interval for food, then she does another 45 mins of magic, songs and and dancing with the kids. So at least I don't have to worry about prancing about trying to entertain them myself when I'll be a few weeks postpartum!
But aside from that I am utterly clueless. I could really use advice on how to sort the following with as little stress and expense as possible, especially as baby will only be a few weeks old:
Invitations- how far in advance do you give them out? Should I give more notice than usual as it's approaching Christmas (8th of December)? How will I even find out the kids names and track down all their parents, will the school be willing to give me a list of first names? Will the teacher/TA mind handing out invites if we're inviting the whole class?
Food- I know some people do little bags/boxes with sandwiches etc instead of a buffet. Do kids seem happy with this? Does it actually work out any cheaper? Will people expect hot food?
Parents- are they likely to stay or should I expect them to drop and run? Which is preferable and should I specify on the invitation? If they stay are we expected to feed them?
Party bags- is it possible to do them for a whole class without it cositng a fortune? What sort of things would you put in/not put in?
Where are the best value places to buy decorations, balloons, party bags etc? Preferably online!
Anything else I haven't thought of? Any tips, advice, do's and don'ts, or general words of wisdom would be very welcome!
Thank you 