As for the 1st question, once you've fixed the source of the moisture, you need to repair the damaged wood. (Or replace it.) You can't clean up dryrot like you can mold and mildew. Dryrot rots the wood, therefore, the damage is permanent. You either replace the damaged wood or repair it with wood epoxy.
If you choose the later, Lowes has a product called Epoxy Wood Rebuilder. Read the container and see that it suits your needs before you leave the store. Other products such as GitRot and Restore-It are available at other Home Centers and/or Lumber Yards. I suggest that you replace the damaged wood since you may find more underneath when you remove it. It's not enough to epoxy up damaged timber unless you know FOR SURE what's underneath.