Important questions:
WHERE do you keep your music files?
WHERE do you keep your pics?
IF you keep them "in the default places", the music will be in the iTunes folder and the pics -should be- in the Photos library.
If you keep them "elsewhere", different instructions may apply.
How I'd do it:
1. Get a hard drive or even a USB flash drive large enough to hold everything.
2. Copy my home folder to the external drive
3. Copy any other relevant folders to the external drive.
Then...
1. Get the new Mac set up as you wish (don't turn your attention to music and pics yet).
2. Connect the external drive and let it mount on the desktop
3. Click ONE time on the external drive icon to select it
4. Type "command-i" (eye) to bring up the "get info" box
5. At the bottom of get info there's a lock icon.
6. Click the lock and enter your password
7. Now put a check into the box "ignore ownership on this volume"
8. Close get info
NOW the external drive is set up so that you can copy anything into your new account WITHOUT experiencing permissions problems.
Next...
a. Open home/music on the new Mac
b. Navigate on the external drive to where you can see the "iTunes" folder
c. Drag the iTunes folder from the old drive and drop it so that it "replaces" the iTunes folder on the new Mac.
d. Once the copying is done, try opening iTunes and see what happens. It should want to update the old library. Does this work? Some updating may occur.
If it does, time to move to pics.
a. You'll need to open home/Pictures on the new Mac, and open so that you can see the Photos Library on the external drive.
b. Drag the Photos Library from the old drive and drop it in to replace the Photos library on the new Mac.
c. Then open Photos. Does this work? Again, updating may be needed.
Again, that's what I'd try.
I don't use iTunes and use Photos very little.
But that's what I'd do.
ONE FINAL BIT OF ADVICE:
DON'T buy a 2017 MacBook Pro.
The keyboards are fraught with problems, and the repairs are VERY expensive once the warranty is up. Surely you've been reading about this...?
I wouldn't even recommend a 2018 MBP (when they're released later this year) until they've been out 3-4 months and its known whether the keyboard issues have been addressed.
If you have an iMac that's working well for you, I'd suggest you "stay put" for the time being...