Voting for the list as a whole means you vote for that party and you're happy with the order of the list. Meaning if the party gets, say, 3 seats, you're happy with the first three people to be elected.
On the other hand, imagine your friend is in 7th place, and you vote for her instead of the top of the list. If she receives more individual votes than the first person on the list, then she'll be first in line filling the seats.
So it doesn't really give you more power in terms of voting total (it's still one vote for one list) but you do have the power to give your opinion on who you want to see elected more specifically.
I haven't seen the pamphlets, but it's possible that the checkmarks show who is already an elected member?
Although it is possible to have non-members of a party on a list, but there are usually few (if any) and it is specified next to their name.