Once you have performed the factory reset your phone will be like it was when first out of the box. It will have none of your user data on it.
When you open up the PlayStore you be asked to sign into your Google account. When the process is finished you will have all your contacts back.
Pictures are stored on the sd card (internal sd card if you have one, external if no internal), so it shouldn't pose a problem. You can always connect phone to your computer and copy to a folder on the computer. Pictures should be in a folder entitled "DCIM".
Note: AppTyrant from the PlayStore will save all your installed apps in their .apk form to a folder on the sd card. It does this when you first open it up after installing it.
After factory reset, just go to folder and copy/paste all .apk's to the root of the sd card (not in any folder, just in the same directory level as all the other folders: /sdcard).
Install by tapping on them and then selecting the install option (this is faster than trying to locate/download/install all your apps on the PlayStore.