200L water pump question

This is the first time I have changed the water pump on my 1999 mercury 200l. I bough it from the original owner and he had never change it.
The boat has been sitting a while. I bough a complete kit. I have a coupe questions. Looking at picture there is a seal I have not pushed all the down.
There was not a seal here when I removed the original pump. Should I put the seal on or leave it off? The next thing I need to know is the pipe that go's
from the water pump to the engine. There is a white tube on the pump the pipe slides into, it seems to fit every loose is this correct?

The black seal on driveshaft is a slinger that keep water from climbing drive shaft and getting in drive splines, push it flush with housing and the white tube is a guide tube for algining main copper water tube, just make sure gromment is still under it in housing to seal copper tube.