I am ratless for the first time in over 10+ years,but I will answer the questions.
A pair of females or males? (pros and cons)
I personally like males better! Heh.
are they are bigger,more cuddly,make better lap rats,will often sit with you while your on the computer...etc,etc.
(I personally do not mind the cons,but many people do),they mark everything (pee dribble everything),they have very large goolies which they tend to drag often and they produce "buck grease" (an orange-yellow grease).
,they are smaller and have softer fur.They do not have large goolies.Cons
would be they are very active,adventerous and playful (some people prefer this though) and are not very cuddly in most cases.
Both sexes make wonderful pets though,so it is really personal preference.
What kind of cage do you have and where did you get it?
I personally love Martin's Cages.They are a great brand.
If I keep a large cage on the floor, can my cats bother or harm the rats?
It could be bad.I find most rats will attack the cats through the bars and defend themselves anyway and one of my cat's has her ears scarred up from a rat attacking her.But some rats stress out way too much.I keep my cages in a "rat room" where the cats are not allowed.
What kind of food do you feed them?
Pet store food is crap and does not contain the proper nutrients for rats.I make a homemade mix for my rats and give them Nutriblock with the homemade mix.As well as things like rice,bread,veggies,fruit,some fish or meat...etc.
Fun toys and ways to keep them entertained?
Most rats will not use a wheel.They love climbing,so ladders and other things they can climb are good.Tunnels,jingle balls,some bird and cat toys,boxes,paper...etc! Also rats love exploring,so free range time is a MUST!
What kind of bedding do you use?
Aspen and Yesterday's News.