In my opinion, all oil filters are about the same. You pays your cash, you takes your chances! In the last 30 years, I have bought dozens of filters from many different known manufacturers and never had a problem with any.
I would go with a known brand from the cheapest supplier, they should all be made to the same British Standard. Avoid ebay, unless you are sure that the filters are "real". I have used Shop$Parts a couple of times and thier stuff is good.
However, pay good money for the right oil as that is the stuff that touches every part of your engine and will stop your chain stretching. I know, I have just spent £3300 having my chains replaced!!!
As for your sump plug, it's just a plug. Find out what the thread is and get one off ebay, Mag ones do work, but if you have that much steel floating round your engine, you are in real trouble already!