Hello Friedolien,
Hey lets get those questions answered so you can enjoy your Mac. The first question, If you want to ensure that all your music is synced up, you will either need to setup Home Sharing to see what is on the other library and import any tracks that have and have not been imported to your library. You can also, at a cost, sign up for iTunes Match so that way when you add any music, it will be reflected everywhere your Apple ID is signed into, including things like playlist. Take a look at the first three articles to give you more information about Home Sharing and iTunes Match. The second question about importing photos is something you will have to click on Import in iPhoto. When you plug in your iPhone, iPhoto should open up but there is not an option for the photos to automatically import from your iPhone being plugged in. Now you can use My Photo Stream and have the photos upload there when your iPhone is on Wi-Fi and the Camera app is closed, the photos will upload o iCloud and then if you open up iPhoto, the photos will import into an event of the current months Photo Stream. Take a look at the last two articles to give more information about importing photos to your Mac from your iPhone.
iTunes: Setting up Home Sharing on your computer
http://support.apple.com/en-us/HT4620
How to move your iTunes library to a new computer
http://support.apple.com/en-us/HT4527
iTunes Match
https://www.apple.com/itunes/itunes-match/
Import photos and videos from your iPhone, iPad, or iPod touch to your Mac or Windows PC
http://support.apple.com/en-us/HT201302
My Photo Stream FAQ
http://support.apple.com/en-us/HT201317
Regards,
-Norm G.