Regarding auto-discovery: have a look into our manual here for creating well-known paths or SRV/TXT records:
It can make things really easy for users
Davdroid is unable to contact with owncloud calendar.
0_1451112603719_davdroid-debug980229518.txt Check uploaded file for debug info.
As you can see in the logs, the TCP connections have been refused. This is a server or firewall problem and very likely not a problem of DAVdroid. Please contact your administrator, or if you are the administrator, fix the network problems.