You should definitely worm and de-flea her straight away. Worming is every 2 weeks at this stage and fleas probably once a month depending on what you use. She is likely to have a big worm burden. I have seen kittens and puppies die from worms and from fleas so it can be a big deal. It may also help with the poo issue. With native joeys we get a wet cotton wool ball or tissue and gently wipe the genital/anal area to stimulate toileting although you have to be really gentle otherwise it can get a bit raw. Hope this helps! Otherwise talk to your vet or an animal shelter. There's bound to be someone there who has raised a few kittens in their time.