You can find a hundred reasons to change things, you can worry about the "gummy stuff" holding the chips and if you want, I can add to that by saying that most probably the peach colored backboard is not conservation board and as a result over time will cause the brochure to deteriorate also.

Personally were I framing a copy of the Declaration of Independence or the Magna Carta, I would worry about it.
Here, I would consider it a real good looking display, be proud of your work and let it be.

On the other hand for the future, on chips I would use a 3/16 drill bit and then and appropriate length aluminum pop rivet to hold them in place.
In the case of Silver Strikes Harris 20% silver solder or plain uncoated brass brazing rod works well. On the newer strikes I recommend a 6010 welding rod using a Lincold DC welding machine and reverse polarity at about 120 amps. That should be good to secure it to a nice metal backing. Make sure to wear a good pair of leather gloves and a decent quality helmet like a Hobart XVS auto darkening model
Epoxy would most likely hold the room keys and the brochures pretty well.

When you go to hang it on the wall, I suggest 1/4 stranded aircraft cable and a railroad spike. I hope this helps with your next project.