GoodDoggie is a certified, professional dog trainer, and her advice is the right starting point.

I agree the best option is to get up at night -- this hastens indoor housetraining because though you can give them space distant from the crate to go -- eg have the crate inside a puppy pen -- then they get housetrained more slowly because you are giving two conflicting messages -- go outside, but sometimes at night you can go inside. Most new puppy owners will need to get up at 3-4am nightly with their puppy for the first couple of weeks.
You don't ever need to shut the door if the crate is kept inside the playpen BUT it is useful to actually crate train your pup to staying happily in the crate for periods of time. Plenty of advice on doing this in the book mentioned below. On feeding the cats -- just feed the pup in the playpen area. You cannot freefeed cats with a dog in the house however -- this breed especially will tend to eat all their food and grow fat! I keep my cats' dry food up on a counter where the dogs cannot reach it.
I'd also advise downloading this FREE copy of Dr Ian Dunbar's well known book After You Get Your Puppy, below. It has types of great advice on training and behaviour -- everything that a new owner will need!
http://dogstardaily.com/free-downloads
It's a shame your puppy's breeder won't keep him a bit longer though? -- 8 weeks is considered pretty young for toy breeds and they really benefit in terms of housetraining, bite inhibition and socialisation if they stay with parent and siblings til 10-12 weeks (more the norm for homing the breed with most reputable breeders these days).
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