Wow you are definately going to have great seats! Your parents must have bought you premium ones

(Usually 5th-8th rows!) -- be sure to Thank them! Hahah
I've been in the Broadhurst 4 times as I said...Row E orchestra to the right, Center Row L orchestra, Row A Center Mezzanine and Row J Center Mezzanine (worst seats in the house -- full price, but the two last rows are only $40 or so!). All for Les Miserables, .. shockingly one time a year from Sunday!
Have an awesome time! I don't have a chance to make it up this year to NYC

, but I totally hope you have a great time!
That's something I would ask about an usher or the stage manager manager about. I heard if you have a matinee ticket stub they will let you "in" at the night performance, seeing as many actors don't come out after matinees, so I would ask them about it, and if they'll let you back in! Also note that Monday night may be a "dark" night for Equus, so you're next chance might be Saturday.
I've never been to any stagedoors with the ticket-issue thing (but obviously with three huge stars all within walking distance...! Katie Holmes is on 45th, directly behind Daniel/Richard at Equus), it must have become an issue of that and of course secruity. Best thing would be to ask, because certainly don't want to miss-up on potential speaking to him as opposed to getting shoved into him getting an autograph :o!
Hahah You'll be suprised if it's your first stagedoor: 1) There are a mixture of theatre/Hollywood people obsessing at them/shoving/etc.! and 2) No other stagedoor except All My Sons is like this! If you see anything else you will see a probably less populated, more orderly, better experience one; such as mine with A Tale of Two Cities and plenty of other shows (like Les Mis!). It's awesome so have an awesome time!!!!!!!!!! Make sure you report on the IP part of the forum about it too!