Its not that it has so much slowed down as people are just waiting for the next update. If you're looking for input you can always open a "What should I do next?" poll and give them several options. Those always seem to keep people interested if you're worried about it.
About BI, the easiest way I found was to pick one of the religions (pagan or Christian) and convert EVERY province to it. Sure you'll probably lose a few to revolt but that works in your favor if you plan it correctly. Since most of the hordes love to descend on France you can always just let France revolt to the WRE Rebels and THEY get to deal with everyone. The ERE, for all it wants to betray you, usually is not a problem as long as you keep a navy around.