No it is not normal. I see you haven't found out how to type the new nexus. volume should work the same. I also always would hit the b, n, x, buttons instead of the space bar.
It takes a few weeks to get used to it. I would hit the letters first, then the home screen button by accident. Anyway back to your problem. I don't have any problems using volume+. On his website you can download it for free. I get great sound from the ringer, messaging, and email notifications. Plus its louder with videos, games, and everything I use. Just he volume is set within the app not through the stock settings. But it works for me and better than paying a few bucks in the play store. Check it out and I hope it works for ya.