First, a word of advice. You'll probably get better, more complete answers to your questions if you make one-post-per-question and drop the post in an appropriate forum. There are many people on the community who only visit and answer questions in certain forums, so you're missing lots of eyeballs by posting the way you have.
On to your questions. (Keep in mind that Tableau may not do things exactly the way you've learned how to do reporting in other projects, so our features may not map exactly to your expectations).
1. Use a Relative Date filter configured to "days": http://onlinehelp.tableausoftware.com/v6.1/public/online/en-us/idcf621f6d-7c5d-4d6f-8d18-27e4439a3f15.html
2. Yes, but it takes some work. Here is an example which shows and hides charts based on a parameter selection. You can reverse engineer it to see how it works: http://www.alansmitheepresents.org/2011/03/changing-viz-types-with-dashboard.html