I don't know much about cleaning the old tank, but I am sure there is information on line.
I will say that I have helped a lot of people who went from salt to planted, and you need to keep in mind it's still complicated, just in a different way. Some things in salt are counter intuitive to planted.
And it does take some effort to learn a new vernacular, and it still takes a good deal of effort to keep a planted tank, especially a high tank full of stems. So get ready for a learning curve. The good thing is that the technical stuff should be easier for you, but there is still much to learn about CO2, light, fertilization, etc.
To me the best way to be successful is to search out tanks that are done in a style similar to what you have in mind. There are low tech, medium tech, and high tech tanks out there and they are quite a bit different. Once you find ones that you want to emulate study their methods, and even reach out and ask questions. I have found over many years that most people in the hobby are happy to share their experience and are glad to help out new people.
Good luck in the new journey. Consider starting a journal so people can follow along and help guide you.