As for the forum search function, once you do a search (using the search box at the top of every page), you should notice on the left side a set of "Filters" that will let you filter by forum. That will eliminate all the non-forum related entries.
The reason your rank nomenclature changed was because we decided to give a different set of names to all the different ranks. Your posts number shouldn't have changed during the switch over. The old system had way too many different ranking names (over 20 different levels I believe), this will make it much cleaner.
Finally, traffic from anywhere in Europe is always redirected to the co.uk site. This is just the way it works. There is no way around it. The co.uk site does have all the same content, so you aren't missing anything.