Yes the wormer will give her diahorrea.

She isn't old enough to have proper control over her bladder or bowels yet so accidents will happen. Take her out at the advised times, i.e. after eating, drinking, sleeping and playing to get her to associate peeing and pooing with going outside.

I wouldn't let her be too far away from the toilet area unless she has just been, the closer she is the more likely she is to make it to the proper area, if she's upstairs on your bed she's got no chance of finding her way to the toilet in time.

You're doing yourself no favours paper training her. You need to be training her to go outside otherwise she will get used to going on the paper and you will have to re-train her to go outside.