As for temperature requirements, It depends on what species you can get. Its not very easy getting one in the US due to their poor tolerance for shipping. But occasionaly, some LFS night get one.
The most commonly imported species is sepia bandensis, although these do not grow big and can be housed in smaller aquariums ( mine is doing well in a 25g), they are frequently sold as 3-4 inch adults with not too long more to live.
Cuttlefish can jet around at an incredibly high speed, and can get infections if they hit something hard while doing so. This is called butt burn, so its best for the tank to be longer rather than taller. Cuttlefish are more prone to inking than octopuses so a Protein skimmer will be needed, activated carbon will also help remove some of the ink. They will usually only ink the first few nights but after that, it gets used to its new surroundings and only inks when frightened or cornered by an object such as a hand.
I'm not sure what other questions might be bugging you so just ask and I'll reply as fast as I can.
Sepia officinalis can get up to ML 45cm so a big tank will be required. I'm not sure what size exactly but I would use a 8 foot tank for them. Feed them crabs, shrimp, crayfish, Fishes can be fed occasionally as the cuttles will need calcium for their cuttlebones. But try to avoid freshwater feeders like goldfish as they may have been treated with copper based chemicals.
You can also try feeding them frozen food. For larger cuttles, take a defrosted whole prawn and drop it in the tank. By using sufficient wriggling the cutlle will take it. this also works with crabs.
1. crabs, and that will be easy for you since you are near the beach
2. as big as you can get... trickle filter and/or large external power filter like a fluval 404
3. 250 - 300+++
4 same as for octopus, but you can have room temp. so ammonia and nitrite nil, low nitrate, SG at 1.025,