I put a 2" thick pad on my mattress and the difference was amazing! It was just a temporary measure as the memory foam was bought for, and is now used on, our boat. But once our new house is built, I’m going to get a 3" memory foam topper for it. And I’ll sleep happily ever after.
As to animal hair and stuff - seems to me unless you use the foam mattress without ticking or sheets, it shouldn’t be an issue. I had a mattress cover and sheets over mine. Of course, I don’t let our animals sleep in my bed… Yeah, like you can keep a cat out of anything.
It’s great that you were able to get the bed for almost half price.
It amazes me that people get upset spending large amounts of money on a good bed. You sleep in it for ( hopefully ) 8 hours a night. These same people drive very expensive cars that they might spend 3 hours a day in. I decided long ago, that I would be comfortable at night, no matter what the cost was. If I wake up feeling good, the day will go better.
They strongly recommend that for tempurpedic beds and the viscoelastic toppers that you buy a waterproof mattress pad to put over the top of the foam and under the sheets. Any sweat or other, um, fluid getting into that foam is not coming out.