A hard reset will give you an option to auto reinstall your Contacts etc and your Apps. (usually from Microsoft account-hotmail/Outlook). Note: your files

ics/Videos/Music/Playlists will
not be re-installed, so you need to save those files to your Skydrive/PC/flash drive etc. And your Start screen will be default so you'll have to re-pin/re-arrange Live Tiles. So some screen shots of the Start screen would be really handy.
To restore your phone using Setup, use the same Microsoft account to sign-in, and you?ll be asked whether you wish to start fresh or restore your phone?s settings from a backup. If you choose to restore, the backup will download and be applied to the device. Likewise, it will automatically download any apps you had previously installed. And when you restore, if you have GDR3 you should be given the option to turn on WiFi first instead of doing it all over cellular(saves you any data charges).
Any Apps you have on your Phone now (Free/Paid) will be re-installed without any new charges. In fact if you just uninstall a current paid app you can re-install it from the Store at no new charge. In other words once installed(even if installed during a 'Free' developer opportunity timeframe), the apps will always be available for you to re-install. As far as the versions....any re-install always puts on the latest version. One note: any settings/app data you have in the apps will have to be re-done to your preferences, so if you have an app that has specific settings that you want to have back in place.....you'll need to take note of those settings.
So before you reset, go to Settings | Backup and make sure these items below are turned on to backup/save to skydrive
- 'app list + settings' (backup on)
- 'text messages' (backup on)
- 'photos' (auto upload on)
Make sure you are on WiFi so that Back up can update.
Hope this helps. Don't worry it should all come back albeit needing a re-shuffle onto Start screen and a small bit of time(maybe an hour at most) and effort on your part.