-regard you first question you can restore previous backup from iTunes ,there is not need of wifi
-Step 1 - connect your phone with iTunes choose ->you's iphone
-Step 2 - choose backup --> click on Restore Backup
- step 3 ->
Find My iPhone must be turned off before “your's iPhone” can be restored.Go to iCloud,
Settings on your iPhone and turn off Find My iPhone before restoring your iPhone.
-Step 3 ->
Windows Vista, Windows 7 and Windows 8 back up the iPhone files here:
C:\Users\user\AppData\Roaming\Apple Computer\MobileSync\Backup,
Mac OS X your iPhone files are backed up at the following location:
~/Library/Application Support/MobileSync/Backup/
-step 4 - finish your restoration