you always have room for BB fish.
You can make it a gillion ways and everyone has their own way to do it. But good quality beer makes a differance, then you just need flour, seasoning and some sort of leavener.
My basic is as follows. this is just a guesstimate recipe, you may need more or less flour depending.
1 bottle beer 375ml i usually use an ale, dark works better in my opinion
1 cup SR flour
1/2 cup rice flour
pinch cayanne pepper and pinch of tumeric
teaspoon or so of baking powder
So it's just a matter of getting the consistency correct. You want it to coat the fish, so a little thinner than a pancake batter would be ideal. Throughout service you will need to feed the batter. What i mean by this is that once you have used it a few times, the flour you have used to dust your fish will thicken the batter, so i like to thin it out throughout service with either more beer, or i usually just use soda water. This will also help give it a bit more kick through service.
As mentioned, there are literally a million ways to do this. Some use yeast, some make a tempura style batter, some use cornflour. Just find an easy way for you to do this and it will be a million times better than packet bought stuff.
As for chips, you need to buy a 'floury' potato like sebego. Cut them into even pieces and rinse off some starch with running water. Pat dry. You can either do it triple cooked which is the best but takes a lot of prep. or you can do the easier double cooked.
Fryer needs to be low for double cooked around 120-130, blanch chips until tender with no colour. cool and dry chips in fridge. Then all you need to do is crank the fryer up to 180-190 for service and finish them off to a golden brown. The longer harder method for triple cooked involves cooking the chips first in salted water until just tender. Then repeat with above cooling and drying in between.
to answer your questions above
you can keep batter out or in the fridge. If the batter is in hot area, you can add ice cubes to batter to chill it down. The flour you dredge the fish in can be kept anywhere during service, but once service is over you need to sift it and chill as you would anything that has fish touch it. Your best off just throwing it unless its a lot of flour. Find some sort of flat tray for dredging the fish, and same for the battering, though a bowl works well also, so you can have room to wipe off excess batter.
The batter will only last one day, it's best to make it from scratch everyday. I find the best is either a beer batter or a tempura. you can make a 'dodgy' tempura batter with the same recipe as above, but the differance is that i wouldn't mix it until smooth, i'd be looking for lots of lumps in my batter. (i have a tempura recipe, but i cannot remember it, if you want it i will find).