You may need all you can get, so I wouldn't eat any more (tho I know you didn't eat that piece deliberately!) Have a look at the wiki guide to Jack, will help to not fall into too many of the pitfalls.
Only what I've read - but I think you can get more candy on the night from 'in their house' villagers - IF you are wearing a look (you know strawberry hat & shirt, burglars shirt & ninja hood etc - I think there is a list of looks in Liquefy's faq).
You need to get rid of that look & into your letters once you are outside - as you could get them changed into moldy/patched shirt or pumpkin head. So wear a cheap shirt & hat while outside. Patterns are OK to wear, - nor do they get taken - but I'm not sure a pattern will get you that moldy/patched shirt.
From what I'm reading it looks as if candy could be in short supply. Thats cos Jack may give lots of duplicates and/or you lose candy to villagers.
Theres 31 pieces of candy to buy off Nook - one piece a day through October, and as far as I can see there will be one piece available whatever level of Nook you have.
Get a few looks ready -strawberry shirt & hat, jester shirt & hat, etc. Liquefy has the complete list of looks in his walkthru faq). Entering the house of a villager at home, dressed in a look, (or costume) gets you a piece of candy off them. And you can do it as many times as you like. Not sure whether you have to change the look, or whether the same one works every time. ???
Yes Bunny day was a very good day to get spare candy - it was possible to get 18 pieces per character. However I think with a few looks and being careful, what you can get in October might suffice.
Not sure what, if any advantage there is, in playing Halloween with more than one character. There probably isn't any advantage??
I hope there is less pressure time wise - 6pm to 1am sounds a good enough amount of time, I found Jingle (8pm to midnight a bit tight to get the whole series). Hopefully this one will be better, but still expect it to be a longish haul.