Hi oluwadare,
#1: You need to change layout for mobile in Template Manager > Layout (tab) > choose layout you want to edit (handheld/iPhone). What you should change is that you create a new block position. In order for you to add Google AdSense you need to create a custom html module and paste the code from Google, then you can publish it to this new position.
You can follow this tips about How to create a new module position.
#2: As I know in Joomla!, user with correspond priviledge can only edit/delete content (here are K2 artiles), creating/posting new articles should be done in backend only.
#3: Which part in your homepage you want to display the Latest Posts? If these posts belongs to a modules, please check in backend settings of that module whether it has parameter such as ordering or not.
#4: We don’t supply such advertising packages, you may find them in JED