Kegging, does the beer need to be clear?

Seriously, Just throw it into a keg, slap the CO2 on it...Wait a Week... Pour a pint, throw it out, pour another pint, and enjoy! Don't make it harder than it is, or any more complicated.

You want to fine your beer in the fermentor as much as possible.

A final finning is offten done in the keg with cold crash and gelitan. Because of the narrow keg usually a week is good to carbonate from top down and fine at the same time. Then the first couple pints are sludge and then clear from there. I prefer to fine this way in the fermentor and save those couple pints, also I prefer to carbonate using a stone or the out tube which stirs up sediment so the beer needs fined before kegging.

I think the reference to bottom drain, is to the pick up tube on the keg not the fermentor. Its best to put beer into the out port on the keg. This reduces exposure to oxygen and infection, being better than opening the lid and using a hose. If you fill the keg with sanitizer, then purge with co2 the beer doesn't get any contact with air. When filing this way You need to release the co2 as beer enters, I air lock the "in" tube into starsan like you would a fermentor, pulling the safety release valve works too but with a slight risk of airborne infection.