If you haven't noticed any noises coming from the mounts, and you have factory ones on there, I'd recommend keeping them unless you spring for factory mounts. The aftermarket ones are all pretty crappy. KYB (not recommended) and Sachs struts don't come with bump stops, so if yours are falling apart as mine were, you will need to replace them. Check out Rockauto for those. I ordered a pair of Rein bump stops, which were actually made in Germany, for just a few bucks each. They're not identical to the factory ones, but they're extremely similar. There were bits of the foam bump stops all over my struts because they were starting to disintegrate from the inside out.
I wouldn't bet on that. I put a KYB mount in my NG900, and it didn't even last 10,000 miles. The biggest issue I've had with aftermarket mounts in my 9-5 is that the nuts aren't welded on very well. Most mounts don't have threaded nuts, and you need an M8x1.25 tap to thread them. I've snapped off three different nuts on three different mounts while threading them with a sharp tap. At the factory, they use special bolts that will thread the nuts themselves (the same bolts that are most likely still on your strut mounts), but you'll snap off a nut or two for sure if you try that because of the amount of force it takes.