Toilet in the basement with a sump pump

I recently bought a new house and was wondering if the sump pump draining into the main drain instead of on its own drain to outside the house is a problem? I have never had a sump pump before and was curious because we get a sewage smell inside our bathroom every once in awhile on the first floor...

How high can a washing machine pump it's drain water out? We want to move our washing machine to the basement and wonder if we can get away without installing a sump pump.

How do I remove stagnant water in my sump pump?

When it rains my sump pump works ,but there is a bab smell?

I want to add a bathroom in my basement. I was wondering if I could run my toilet drain into the sump pump hole. ( I have my own septic symstem and the drain leaving the house is 4ft. Above the basement floor). Also, would this need to be vented? The toilet would be about 6 to 8 ft. From the...