New dog owner - vet question

Hello,

we adopted a 11 week-old puppy a couple of weeks ago and went to a vet with her this past week for a puppy exam.

I did not feel very comfortable after leaving. First off, they did a fecal test and found out that she has worms. We were given some pills for her and they also told us to start her on heartworm prevention, gave us a 1-month free sample of Sentinel.
I did some research and found out that you should not start your dog on heartworm prevention until the dog was tested for it. They did not test her though and still told us to start the pills.
We did not give her the pill yet and are thinking about switching to another vet.
Another thing is that the technician was talking to us about how to housetrain our dog and after we told her that we are not crate training she basically told us we are not doing it correctly then and that dogs her age can hold it for about 8 hours! She is only 3 months old so i always thought they can only hold it the number of months they are plus one??

What do you guys think?