Make sure you block up any holes they can get into e.g. behind the kitchen units, up a chimney, behind a bookcase. Kittens can squeeze into surprisingly small spaces and vanish, leading to panic charging round trying to find them!
Winter now, but bear in mind that they won't be able to go out until they've been jabbed & neutered so consider what you will need to do about windows etc. when the weather gets warmer - I use Flatcats to stop my indoor cats going out.
Get ceramic or metal bowls, plastic taints the taste. Place the bowls well away from the litter tray, and ideally have a decent gap between the food and water bowls. Start on the same litter & food they have been on, you can gradually change over time if you want.
Think about confining them to one room at first so they can acclimatise, then play it by ear to let them explore.
You may want to look into a cat tree, as many cats prefer to be up high.
You don't say if you have DC. If you do, keep an eye on their behavior around the kittens and if they are toddler age then never let them together unsupervised for both DC and kitten's sakes. Kittens can be very delicate and small children quite rough!
When you get your insurance, please consider a lifetime plan. That way, if they get any chronic condition it will be covered for life rather than just the year it appears in - my DSis ended up paying well over insurance premiums every month for epilepsy meds for example.
Post pics in here as soom as you can. Kitten tax is very important!