The first one I've seen before when the SSRS service account doesn't have full permissions to the RSTemp directory under ReportingServices directory. So you may want to check that.

And then you do have a recycle going on so you may want to adjust the time for RecycleTime. It may just be hitting at times when the report server is busy, although memory pressure can kick it off as well.

This article goes through how this works, where it's set, etc:

https://msdn.microsoft.com/en-us/library/bb934330(v=sql.120).aspx

I'd probably want to check with Perf Mon and see how the memory is on that server. It could be under powered, maybe not. But some of what you are seeing can be due to memory pressure.

Sue