That is a LOT of mostly good advice! I've been ~15 times now and have to say I've never stuck to any plan for what I was going to do. Once you get in and start watching golf it all changes. We usually plan where to put our chairs (typically 18 or 16 green) and then wing it after that. Never been disappointed! Of course my attitude may be/have been different if I knew it was my only day at the Masters...
Don't pass a bathroom with no line - when you really have to go there may be quite a line. With that said, these are the most efficient bathroom lines in the world!
There is a check-stand just before the main gate on the left that will check your cell phone or your wife's bag. Many days we don't go straight back to the hotel and it is nice to have my phone after leaving the course in the evening. If you park on site you can leave in your car obviously, but we are typically taking the hotel shuttle.
Also there are free phones (free US calls) throughout the course - mostly by the main concession stand near the merchandise shop. Write down any numbers you may need and bring them with you.
If your friends give you sh@t about wearing a Masters shirt or hat, introduce them to JK and then get new friends. With that said, I would recommend wearing only one piece at a time.
Chairs - I like the chairs. As I said we typically put them down and then leave them. Write your name on the card in sharpie or use a business card - they all look the same
. I've left umbrellas, rain gear and jackets either on my chair or in the sleeve the chair comes in and nothing has ever been bothered - nowhere else would I leave expensive gear and not worry at all. It's nice to be able to have somewhere like that for me. There have been years we have never gotten back to the chairs but that's ok also. With that said...take your time on spot selection. All views look great when nobody is sitting in front of you! We'll have buddies sit in the empties in front of us to see how the view changes. And make sure you can see the hole - not the bottom of the flag, but the hole. Brutal when the flagstick comes out and you can't see.
Binoculars are a very good idea. Let's you see action from a distance, check scoreboards, and is surprising good for watching putts when you are a bit far from the hole.