I tested this with two different 64-bit 15.04 installs:
A) fresh 15.04 install (just did it this week) - installing skype works flawlessly with a standard approach of adding the partner repository then apt-get install skype.
B) fresh but overused 15.04 install - this box had a lot of additional software installed (over 15GB). It wasn't upgraded from a previous install like yours. I had exactly the same errors as you. None of the usual fixes out there would work (apt-get -f install / clean / autoclean / whatever - none worked)
This shows that the problem is with your packages. I even tried aptitude to solve the conflicts, but it wanted to uninstall over 500 packages from my system! (no, thanks!).
Do a fresh install (15.10 will be available within a few days!)
Try to use aptitude to see if it can give you a better solution in your specific case. I'll improve this post with examples upon request.
Install all dependencies by hand to get Skype to run on your messed up 15.04 install (its probably not your fault it got messed up - this is likely a bug). I tested this and it works, so that I have Skype on both (A) and (B) above. Two ways you can attempt this:
apt-get install recusivelly all packages above, forcing install when necessary, even though apt-get is complaining. I couldn't get this to work.
(worked for me) Install each library by hand by fetching it from the repository. It is more of a craft to get this right. However, it might be worthwhile since Skype is so central that you might well need it very badly.
I will describe this in a couple more edits, but basically involves using ldd, apt-file find, apt-get download package_name:i386, dpkg -x package_name*.deb to decompress, then an ldconfig trick using /etc/ld.so.conf.d. I could just post all libs directly to you, but its 600MB worth of *.so's....