Re: dryer vent
Insulate the duct where it runs through any unheated space, such as the attic. What is most likely happening is that the warm, heated air from the dryer hits the cold ductwork in the attic, condenses, and runs back down the duct pipe. By insulating the duct, you'll reduce the amount of condensation because the duct will be able to warm up. There may be some initial condensation, as the pipe will still be cool when you start the dryer.
Also, dryer joints should not be secured with screws or rivets. Lint can catch on these protrusions inside the pipe, build up, and block airflow or catch on fire. Joints should only be secured with foil tape designed for heating ducts. Ordinary "duct tape" cannot withstand the heat. You may have done it correctly, but I just wanted to point this out as incorrect installation is common.
Generally, it's not recommended to go over 6' upward with the dryer vent, as it increases the likelihood of the vent becoming blocked. I realize that in your situation, routing the vent downward may not be an option. Since you are going vertically for such a long distance, be sure to clean the duct pipe at least annually to prevent excess buildup.
The "Senior Member" designation under my name doesn't mean I know a lot, it just means I talk a lot.I've been a DIYer since I was 12 (thanks, Dad!). I have read several books on various home improvement topics. I do not have any current code books I can refer to. I was an apprentice plumber for two years.