Question
Hello! I have several questions in one, I hope you don't mind, :).

First, I'd like help in identifying my 5 cacti. Sadly, I do not have any photographs, but I have DRAWN pictures of them.
I didn't get the spines correct exactly, but I added measurements.

The first cactus I own, and is my newest one, was sold as a "Coral Cactus." I did a little research, and that is one of its common names. I don't know how to describe it, but I bet you know what I'm talking about. It's green, with the curls/folds/fan part being light green and pink.

I am almost certain that my middle sized cactus is Cereus peruvianus, although it was sold as a "Saguaro". Its spines are about an inch long each, and it grows very fast. It was only 2 inches high, and 6 months later it is now about 7 inches.
My smallest cactus is just a green stem with a huge bulky orangey red bulb on the top of it. It has not grown at all in the 4 months I've had it.
My small, round cactus was sold as a "fish barrel", but I am almost certain it is a baby saguaro. It has grown upwards about an inch in almost a year of having it, and has grown in circumference perhaps 5 cm.
My largest cactus, which is almost 2 ft high now, I have no idea. At first, after doing a little bit of research, I thought it was also a Cereus peruvianus, but its spines are completely different. Where my middle sized has 1 inch long spines, this one has 2mm long spines, and has a lot more. It is very strange, because it has dozens of very tiny 1-5 inch long cacti stemming out from the base. The 2 longest stalks are the ones actually growing, as they have segments, but the dozens of smaller ones have not grown as much. A few were only 3-7 CM when I first purchased it, they are now perhaps 1 inch, and various tiny ones have sprouted. The picture I drew of it does NOT do it justice.

My cactus art is not very good, but I did add some color to it at least. :)

This is a link to the huge one:
http://i3.photobucket.com/albums/y82/Desirai/Cactus_02_x1.jpg

This is a link to the other 3, minus the coral cactus.
http://i3.photobucket.com/albums/y82/Desirai/Cactus_01_x3.jpg

If you are able to help me figure out what they are exactly I would so appreciate it!

Now, for my next question... should I repot them?
all of them, save for the newest coral, is in the same pot. A very huge pot, mind you (about 2 ft across). Now, my biggest cactus is taking over the other 3 smaller ones. Should I repot them all in separate pots?
I'm very scared to do it, because the way the middle and largest are growing, I'm scared their segments will break off. I can't break the pot they are in.. it's like, anti breakable. Plus I don't want to, it's pretty.
To begin with I put them all in that one pot for a few reasons:
1, it was big, hehe. 2, I had no other pots available. 3, I didn't expect them to even survive.

I had 3 other cacti along with the 4, minus the coral. One was just like the round one except its "spines" were like hairs. It was very fuzzy, same with the second one. It was like an elongated version of the fuzzy round one. And the 3rd was like the smallest one I own, the one with the huge bulb.
I'm not sure why they died, they just started to shrivel up one day and next thing I knew..they were all like clumps of gross slimy stuff. Did I under/over water? I watered them as much as I watered the others I owned.

Anyway, I live in Alabama USA. 8/12 months of the year it is very warm, so I have left them outside since about March of this year. I got my very first one about last October, and they all stayed in the house til earlier this year. I'll be bringing them back in about December when it starts to get cold.

anyway, forgive me for this huge wall of text!!
Any and all help you can give would make me so happy~~~~!
Thank you! :)

Answer
Desi,

I almost don't know where to start! Anyway, your drawings are fantastic, but they really don't help me to identify your plants, although they do help me exclude a few. Anyway here we go:

A Cereus peruvianus is blue in color only has about 8 ribs and the spines are not that long (especially when young). A saguaro is dark green in color has as many as 20 ribs and has many long spines (and can actually grow pretty quickly).

"Coral Cactus" can be many things, however if you "Google" coral cactus in the images area, you may see your plant.

"orangey red bulb on the top" This is a "Moon Cactus" which is one cactus grafted onto another, check out this website: http://www.cactuscollection.com/faqs/index.html#Anchor-Grafte-30651

Your "Fish Barrel" is a fish hook barrel cactus is a Ferocactus wislizeni.

As far as replanting, they should be fine together unless you want to separate them. The one that rotted could have been from over watering. The problem is that you have cacti from all over that require different watering schedules, however if you water them only when the soil is dry, they should be OK.

Please let me know if I missed anything. Thanks!

Greg