"How many properties occupied the property where the Mint sat, and then became the Horseshoe?"

Good question!

The photo of the Mint, on page 117, has a great shot of the corner entrance. That entrance was on property that used to be the Birdcage casino, in 1958-1959. (Looking at the earlier chips, you can see that the corner entrance isn't pictured.)

As for the tower, The Mint opened in 1957 and closed in 1989. Del Webb took over the ownership (or at least a large share) in 1966, and I'm pretty sure he's the one that added the tower...so it was probably added circa 1966-1967.

The Birdcage was at one end of the block, the Horseshoe was at the other end. Other casinos, including the Mint, were between the two. Eventually the Horseshoe expanded to take over the entire block. Here's the addresses and dates that I could find:

100 E. Fremont: Birdcage 1958-1959, Mint 1957-1989, Del Webbs Mint 1966-1989

104 E. Fremont: 21 Club c. 1940's-1940's

116 E.Fremont: Jackpot Club 1941-1945, Club Savoy 1945-1949, Khoury's Club Savoy 1949-1953

118 E. Fremont: Boulder Club 1929-1960

124 E. Fremont: Kiva Club (in the Apache Hotel) 1932-1934, Apache Casino 1932-??, Western Casino 1941-1942, New Western Casino 1942-?

128 E. Fremont: Western Club 1940's, Rex Club/S.S. Rex 1945-1946, Eldorado Club 1947-1951, Horseshoe 1951-2004.

Oh...you asked about the land... Someone once posted a link to the Las Vegas county clerk's office (or registrar of deeds, or something like that) that showed the owners of the different parcels of land that the Horseshoe is on. I couldn't find that in the archives, but this article might answer your question:

http://www.reviewjournal.com/lvrj_home/2004/Feb-20-Fri-2004/business/23258589.html