Hey Dave,
I use EZ Drummer. I had a ripped copy, but it is such a great Plug-in and my conscience got the better of me so I ended up buying a copy. Before that I was using MT Power Drums which was OK in a mix and also Sennheiser's Drum Mica. Both of them freebies.
Drum Mica is a very nice all acoustic sounding kit with the choice of a several different Sennheiser mics. It has 13,000 samples and about 1,500 drum patters. But both EZdrummer and Drum Mica are fairly large Plugins and my old computer was struggling to handle both so I have opted to stay with EZD. For the challenged like me, EZD was the best choice for song writing.
You got me beat with triggering drums with the bass, way past my pay scale I'm afraid.
Cheers mate
rob