Those repairs should be well within a DIY'ers ability.
When you write the "Cleat let go" do you meant the screws that fasten it have pulled out? If so, what type of cleat is it, where is the cleat, what material is it mounted on, is the load on the cleat horizontal or is there a vertical component? I would probably recommend moving the cleat - it doesn't have to be very far but maybe there's a better place for it. You need to understand why it failed.
With regard to the centerboard line the repair depends on the system. I would start by rolling the boat on its side and extending the centerboard all the way and see if the attachment for the line is accessible. If so it is fairly simple to thread a new line (You may need a stiff wire as a leader). Attachment to the board can be as simple as a bowline. You don't need fancy cordage. Just look for something abrasion resistant and that doesn't float.
If the attachment isn't accessible you may need to figure out how to remove the board but I'm guessing that won't be necessary.