The top line in the snap above is the right-hand part of bar 7. The bottom line might help you work out how to count it. I've rewritten the dotted eighth note as a sixteenth note tied to an eighth note. If you took all the ties out it would be the ra-ta-tum-tum rhythm from 'The Little Drummer Boy'
Firstly try playing the phrase leaving out the tie marked with an asterisk. Remember the half note starts on the second beat of the bar.
When you're confident you can play it without the tie, try reintroducing it, but make sure you keep feeling rhythmically where the half note starts, even though you're not articulating it any more.
You also asked about the bass clef - usually the bottom stave starts with a bass clef, but it can change. This makes it much easier to read left hand parts that go higher than middle C - helps eliminate ledger lines that would be required if the part were notated in bass clef.
Finally you asked about bar 13. Try counting this out really slowly, and mark in pencil where the beats fall. The snippet shows how you might do it. If the beats are quarter notes, just count 1 2 3 4 If they're subdivided into eight notes count 1 & 2 & 3 & 4 & - and if there are sixteenth notes you can count 1 e & a 2 e & a etc.