Since doing a hard reset I find that Apps won't complete downloading from playstore.  After tapping install and accepting any necessary access, downloading seems to start - in that the bar travels across the screen.  Then nothing changes - for up to an hour. The app isn't installed.  I've had a few that have installed but most don't.  Running android 5.1.1 and connected via wifi close to router.  Speed test indicates around 18MB downstream.
Any suggestions on the problem and what to do about it?

Too often when connecting by wifi to my router my nexus hangs on 'getting ip address'.  Sometimes switching wifi off and on again helps but not often.  Anything that can be done to get over this?  There is a PC connected by cable and a laptop by wifi, but both these are usually in hibernation when using the nexus.

Just got a nexus 7 and want to move a lot of epub files from my PC to the nexus.  Any quick instructions to save me trial & error and a lot of searching?  (I'm totally new to Android)