Actually, no. The three current ferries were built 2 in '72, and the third in '76. Well before even Epcot.
As for the monorail trains, they started with 10. The original Mark IVs were extended by one car in the early 80's, and 2 more trains were brought in '84. The Mark VI's remained at 6 trains, but carried more passengers, though I do not know how many. But in any case, there has not been a significant increase in capacity since the mid 80's. In fact, between 2009 and 2011, after the crash before they rebuilt the cabs, they actually had reduced numbers.