Yes you heard / read right. Power level will be reset at the start of each season and all bonuses from the previous season will be stripped from your armor & weapons. There'll be new bonuses introduced and those will only go on to new armor & weapons. Ontop of that there will be a brand new selection of hand picked must use exotics.

I’m going with…. Maybe. We don’t know enough about the activity or boss tuning for anything. The armor/weapon buffs and selected exotic enhancements are likely only going to improve things to make them more fun, but I don’t think they’ll be necessary to do any of the new content. I could be wrong though and you’ll be booted from every fireteam and all requirements will be “new gear only.” There won’t be anything definitive until it’s released so you’re just gonna have to wait it out if you want a true answer.