How can I tell if my Iphone is being spied on or if it has been jailbroken?

I'm trying to find out if my Iphone has been jailbroke and had one of the Iphone spy apps installed. I left a my phone in a friends car and since then it has just been slow and he is pretty tech saavy so I wouldn';t be suprised if he did. will a restore and manually inputting my contacts erase all apps installed?? I just recently today updated to OS 4

Many Thanks,

john