My advice echos buzz2400's
We've been twice - first with EE and two years later without EE. When we had EE, we went to the EE park each day until it got crowded, took a lunch/swim/nap break and then headed to a different park for the late afternoon and evening. Without EE, we stayed in the morning parks until the early afternoon (encountering more crowds), took shorter lunch/swim/nap breaks and still got to the second parks later than planned every day. We still enjoyed our second trip, but without EE we used FP more extensively to avoid much unnecessary waiting.
The hour "lost" by getting up earlier to take advantage of EE is more than made up for by the lower crowds, the cooler temperatures, the shorter waits and the longer nap times

in the afternoon.
As far as your specific questions go -
Worth it - YES!
Strategies - Head to your favorites or the more popular attractions. Grab a FP for the most popular ones (so you can ride that one next or twice) and then get in line. Leave the EE park when the park gets too busy and lines get too long, either hopping to another park or to take a break OR enjoy your late breakfast PSs (See below).
Do EE at MK before the Pirates Cruise - You can get a lot of no-wait riding done in that 1 3/4 hours, then hop the monorail for the GF.
Get the late PS for the EE park. You will need the break and the crowds (and wait times) will be starting to build. Get FPs for your "next" attraction before you eat so that you don't lose time waiting after breakfast.