Those different colours only mean different makes(Red, Blue, Yellow and Green = 4 Importers using 4 different makes based on our flag colour)......all of them gas cylinders contain the Liquified Petroleum Gas (LPG) and perhaps some contain Butane and Propane- especially the camping ones.
BUT, the thing is: Each make has their own connector jacks that fit into the head of the gas cylinders...in other words you can't use a red gas cylinder connector jack for a yellow cylinder and vice versa. Same goes for the other makes.
Some recommendations: Have a walk around where you live and visit the shops and the nearest filling stations and pay attention to the make of gas cylinders they sell. Its simply a question of convenience really.
When I was back in Mauritius I was using both the Yellow and the Red ones because I lived in town and both were readily available...so in case one ran out and became scarce in town, we could rely on the other make.
The first time you "register" with the company you will have to pay more for actually renting one gas cylinder or even 2...then its just a matter of returning the empty ones and getting new ones if you get the picture.
The cable connecting from the cylinder to your cooker (yeah they should work fine provided you have the proper jack fittings) has an expiry date and you need to check them regularly and replace them every year.
To conclude, I would say, although gas cylinders are used for cooking and sometimes for the shower and as such require no piping to be fitted like the central heating for the houses in Europe they do however become a potential hazard if not properly looked after (I mean checked if properly closed, loose fittings, severed conecting cable e.t.c).
Best practice is to build a compartment outside the house (properly explosion proof plastered) and to keep the Spam. You still need to cater for your cooker though...don't forget to switch off...
Well I guess that was a bit too much and boring. But Best practice is Safe practice. Take Care
(the oil and gas expert :D)