I cant open my applications iPhone 3G

I have been having several problems with my iphone 4S  : (someone please help!)

    - I cannot access my applications. Whenever I push the application, the phone screen slightly blinks for a second, but it will not enter the app and stay on the home screen.

    -  Siri cuts me off before I finish telling her my request, which she doesnt understand since she cut me off before I finished telling her :/

    - The contact that I add dont appear on the contact list. The only numbers that show in the list are the ones that were synced from the begining. Thr numbers are in the phone though because siri is able to make calls to those numbers. The numbers just arent showing up on the contact list.

    - Final thing that just started happening, which is probably a new network error is that my voice started to echo in the middle of a call, and a few really weird technology beeps also make appearances in the call.

   I have restored the iphone. (I clicked the restore option on itunes and then restored the backed up copy of my phone's information from icloud. I cant lose a lot of my information which is why I chose a backup option) Somebody please help me fix one/all of these problems!