Your skype issue, can you be more explicit?
Are you using earpiece or speaker?
If it's a speaker issue, does this happen with regular calls as well and whatsapp calls / viber calls?
Well, I can tell you I haven't noticed the problem until I made a Skype videocall, this means that everything is working fine outside Skype app..
I can hear loud and clear the other person, but they just cannot hear me: the microphone doesn't catch any sound..
No problem with WhatsApp video calls or Hangouts.. though