Gosh, you know your stuff. But then, you've got most of it 
By DS, are we referring to the little catalogue the comes in the middle of the big one and/or "accessories" section of the the Playmobil website. Is the DS stuff the same in every country (although perhaps a year adrift of Germany)? I have just bought 3708 from DS last Thursday (no people, just the car as 7844), yes you're right 3866 is 7450 in the add on catalogue here, 4146 is a new set here, 4223 is an add-on, is 4635 one of the ones in the Lucky Dip bags? I am surprised about 5360 being DS - is that not the one that goes for millions on EBay??!! I don't think I have ever noticed 7146. When the boy is up and about in the morning I'll look through the old catalogues as he keeps them close!!!!!!
Yes DS or Direct Serice is also called Add-Ons.
No every Geobra web sites have the same things. Some do get the production delay you refer too and some times a site will find a stash out of a mysterious hole. I have seen old western steck sets just show up one day for "best buy" and in Canada the old 5300 extension all of a sudden showed up¿
Yes 4635 is an American football player, not the exact same colors but still usable and hopefully he will not fall apart when tackled
the burning football print has to go though
5360 was re-released in the new color as 7477. It did and MIB still goes for a lot but the price seems to be dropping as we can now get the 7477
7146 was recently dropped from DS and I still see it in stores that carry bags. I was able to get as many as my pocket could handle
