The first question wasn't too hard, but required a little thought. Going by the position of the blank space on the wall, the missing date had to fall between the 2005 and 2007 MDS's. Also, we see that this list is being written on '#1 Right Door', so we have to stop and think about what would be relevant to one of the Big Doors, because what else would earn such a large portion of real estate back there? I couldn't think of anything that relates to MDS's other than the fact that the Big Doors change for the MDS's, so it was simply a matter of deducing the only other time the Big Doors were redone between 2005 and 2007 - namely, the Season 35 redesign.
The second one drove me, like I'm sure the rest of you, bonkers. At first, putting it with the other two pictures, the only prop I could think of that was big enough for the picture was the back of the More or Less sign, but that seemed like too many items to be the back of something with nothing more than lights on it. So, after way too much thought and coming up blank on my part, I asked my dad (who's a bit of a handyman) how old the prop looked, and showed him props from that era until he saw one he liked...and we were way off there. Thankfully, John gave everyone a second chance, while also expanding the picture to include a dead giveaway. That shape in the lower-left corner is quite obviously the 'card' on the lower-right side of the Stack the Deck prop. This took me maybe eight seconds after seeing the second picture.
The third picture, however, was really easy. The only way you could possibly miss it was to stop looking after the first switch (Bag and MoL), thinking you didn't need to look for a second (Push and Cliff.)
Oh, and I took the liberty of changing my signature again, John.
