Cats usually have problem-free deliveries, and it's by no means unknown for them to take a rest between kittens - one I fostered had 5 kittens then a 6th 8 hours later.
She will do what she needs to do, she might want to be alone or she might want to be with you. When she delivers a kitten she will probably break the cord and then eat the afterbirth, if not use clean fingers and tear the cord - don't pull on the kitten's tummy. It tends to bleed if you cut it.
There is lots of information on the Internet - the FAB is good.
Have plenty of stuff around for bedding but make sure it hasn't got lose threads that kittens could get caught it, and check as they are delivered that their cords don't catch on each other.
She will mostly stay with them for the first week, and they should look like plump furry slugs after that week. She will need plenty of good-quality food from now on - usually pregnant and nursing queens are fed kitten food as it's higher in protein. The kittens will probably wean themselves - the ones my friend bred did so by swimming in the food and then cleaning themselves!
She can be neutered once they are eating solid food, though she may continue feeding them afterwards. Watch out though - some females call again when their kittens are as young as 6 weeks old!
Also check with your vet about flea and worm control. Worming kittens is often done using Panacur paste and I think you can get that without a prescription on the Internet. You can also get Frontline without a prescription either at some chemists or again on the Internet where it is cheaper. I gather it's OK to use it on pregnant cats but not very young kittens, so treat her now and also wash all her bedding (if any). Fleas can really drag kittens down.
But most of all, prepare for a lot of amusement for 10-12 weeks! And be prepared to be very fussy over who can have one or two of your previous babies. It really is fantastic to watch a cat bring up kittens, enjoy it.
PS I see you live in Germany - I'm assuming the same applies over there as to what you can get without a prescription.