What happens with my iphone if i connect it to another computer?

I plugged my iphone to my friends computer when i first got it to download some of her music, it was only later that i heard my phone can only be connected to one computer. We're not really close anymore because she moved a town away and i desperately need new songs. I have my aunts computer which is the one i'm always using and i want to connect it to itunes to download all the songs i want / missed the first time. Now
1.Is this bad for my phone?
2. Will it deleted EVERYTHING?
3. What are the step I can take to prevent my photos / contacts from being deleted?

Please help me out and be very specific. I have an iphone 4 just in case that information is a need to know kind of thing.

You can authorize 5 computers! Go ahead & connect to your aunts. Once you do, sign into your acct., from there your device should show up on the left side (whatever you named it)! After that click the back up button & it will back up all the stuff you have. & you can also go into the settings in iTunes & authorize & deauthorize, the different computers you have synced with your phone. It will show your old friends computer(which you can deactivate your acct.off of). Just make sure you back up your stuff first! There's a new version of iTunes (so you would have to update 1st (just in case you haven't done it, so before you connect your phone, click iTunes & update). & there's also gonna be a update to ios 6 on Tuesday (free, but make sure you back up your stuff first)! Hoped this helped