For the ethernet failing issue did you ever try a SMC reset? Sometimes helps:
These are a couple of suggestions that have worked for some in trying to resolve connectivity issues. Add these OpenDNS settings in Network preferences (make a note of the number that is currently in your settings in case you want to revert):
http://use.opendns.com/#mac and then test.
Some on here don't advocate using OpenDNS, many others do. I use them myself. More info on OpenDNS:
Add a new Network Location (following instructions under 'Making New Locations':
http://support.apple.com/kb/HT5289 and test it.
This last suggestion has worked for me in the past.