I have girls and they are very affectionate and snuggly - but I work from home and have them out with me all day... they have various blankets and cosy pod things on the sofa and they tend to run around like mad for a bit and then go to sleep one each side of me.
The more effort you put in with them, the tamer and more snuggly they are.
We use strawberry or apple yoghurt drops (amazon or ebay) as treats and they know the rustle of the bag which is very handy if they have gone on a free roam and I need to get them back. It's like a heat-seeking missile attack when I rustle the plastic.
They are chewers so don't let them near cords (headphones, charger cables etc - they love them). Also don't believe anyone who says they don't like peppermint or eucalyptus... mine would sell their sibling for a cough sweet!
Supreme Science Selective Rat food is what mine have as their main diet - looks very dull but they love it and Amazon delivery.
We have this cage: https://www.amazon.co.uk/gp/product/B097T7S7B2/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
It's no use for teeny ones, but once they get adult size it's perfect. I have this one for babies (it's not that big, but mine spend a lot of time out of their cages): https://www.amazon.co.uk/dp/B07KT4RVVY?ref=ppx_yo2ov_dt_b_fed_asin_title
I spend a small fortune on hammocks - they love sleeping in them, and ripping them to shreds. Some last longer than others!
They are the sweetest, nicest, funniest animals I've ever had - but they have very short lives so a lot of heartbreak.
If you have ones that are a bit nippy, squeak at them and they seem to get the message fast. I've never had a biter but the babies can get a little enthusiastic playing. Mainly you will be licked to death.
Definitely find a vet that will see rats - sadly you will need one every now and then.