How can I control separation anxiety? I believe that is the issue as well.
Sadly this is the side effect of being the pack-leader.
This usually has to be done in baby steps, and regularly. It is hard to accomplish if you don't stick to it.
I started off with small sessions. 10 minute trips out of the house a few times a day for a while (I think 2 weeks). Then start increasing the time gradually.
Me, being a nerd and all :p, I have a security camera that connects to the internet. So what I did was went outside to a bench, which was within my wireless range, and watched my dog via my laptop. Timed him til I noticed he started getting nervous and might start ripping things apart, or started to make a lot of noise.
I then started pushing the time longer and longer. Eventually I could take trips out to friends for hours before he started to get upset.
Just be careful not to give in the instant he/she starts throwing a tantrum, and DON'T start soothing and comforting the dog when you come in. Just act natural like it's no big deal. Actually just ignore him a while. Even if he comes running up to you and wanting attention.
If you do, the dog will pick up that you can "hear" his cries out. And will never stop.
Eventually they will start understanding that you do indeed come back.
Again, I did this with my previous dogs, I will be using the same technique on my Basenji.