First Problem: No idea - sorry.
Second Problem: What you're experiencing is a limitation of Windows / DirectShow. As a general rule, only one app at a time is allowed to use the camera.
As you say, shutting down AbelCam when you want to use Skype is one solution.
Another solution is to use a "camera splitter" program. One free one is "Manycam" :
http://manycam.com/ I have used Manycam a little bit - it seems like it works as advertised, it didn't destroy my system or bring me any malware, but I noticed it eats a lot of CPU.