Hi

Yes, Reaper is a very good value for money multitrack and MIDI recording package.  I use Cubase personally, but that's because I have used it since version 1 and have kept up with the upgrade programme over the years, but had I been starting now, I would almost certainly have gone down the Reaper route.  I don't think you'll have any trouble using plugins like EZ Drummer.  The HD400 will act as your audio interface.  I would recommend that you download the latest full-featured version of Reaper and try it before you buy it.  You get thirty days normal use, after which you get continued full access usage, but with a 'nag' screen when you start the program.  If you intend to use the application, it is so cheap for the home use license, that I don't believe it is in anyone's interest for you not to buy the license as it represents excellent value for money - I'm not suggesting you aren't willing to pay the $60 license fee BTW as you clearly are from your post

Nick