I drain by removing the drain plug when the engine is hot, put a pan under and let it drip for several hours, I only put the plug back when it stops dripping.
On the filter housing I get in it with a rag and absorb about everything deep down that is visible from up top, when I put a new filter in the housing is clean and dry.
I change oil about or little over 2K miles, Delo 15/40 diesel rated.


Vahe
240D 77/350K