We are adding stairs to our deck (approx. 9' from the ground) with a turn at 32 in., making the first run 72 in. We are using 4 stringers to ensure support for this first run (our steps are 42 in. wide), but are wondering if it is also suggested to add support posts on the sides (we will have four on our base at the turn)?
You should review the code for your particular location. Where I live, we use International Residential Code 2006, many jurisdictions use the 2009 edition. The IRC code has two pages devoted to proper construction of staircases, with diagrams and discussion. Talk to your building inspector, they should be able to tell you which code you need to adhere to. If you have no building inspector, or do not need to meet code, I would suggest following IRC 2009, you can't go too far wrong if you follow it.