I have 2 questions about my 4wk old kitten....?

I have bottle raised her and nursed her that way. I've tried to introduce soft canned pate but she don't seem to get it. I need to wean her. She's having diarrhea and I can't have her thinking the bottle is the only way to eat. How can I get her to eat 'real' kitten food? Also, with this problem comes the problem of what to do until she is litter trained? When should she be litter trained? 'Cause right now like this, she can get to be a stinky little thing that I have to bathe daily. Plus I can tell er little bottom is sore, too. Help!! Thank you SOOO much!