Share your experience!
For the loudspeaker,uninstall updates for chrome or even disable it in settings-apps-all.
For wifi,take a look here:
http://talk.sonymobile.com/t5/FAQ/Wi-Fi-problems/m-p/348104
For battery backup,boot your phone in safe mode,see if anything improves:
http://talk.sonymobile.com/t5/FAQ/How-to-boot-your-phone-into-safe-mode/m-p/348008
thanks a lot.....
Keep us updated,hopefully I can help you a little.
You could visit a sony service for further assistance:
http://www.sonymobile.com/global-en/support/contact-us/