1929 Hudson questions

Unknown

A couple of questions to the lubrication system of 1929 Hudson:

1.) It looks to me like the oil in the oil pan is not drained out when draining the oil from the sump, when changing the oil. When adding the new oil, it will then mix up with the relatively large amount of old oil left in the pan, correct??

2.) as there is no bottom drainage of the pan, won't sludge and dirt build up in the pan over time??

And one question more:

behing the camshaft sprocket there is a washer. The washer is provided with a hole for a small pin. What puzles me is that the washer does not have a tight fit. Do I miss anything? Won't it rattle while the motor is running?

Thanks for your advice:-)

Gert