In theory the 50 state thing is nice, but in the practical sense it's very unlikely a CPA would not be allowed to represent their client in any state. I've never had some question a POA in any state, and the POA only says CPA due to limitations with my software/can only check one box.
The EA exam, like any exam, will teach you a ton in the study process. I had 10+ years experience at the time and I still learned a lot (although most is "book answers" vs real world answers if you know what I mean. Besides the education and letters behind your name (and hopefully higher billing rate) the EA is useless to a CPA.
I only did the EA because I was not eligible for the CPA exam at the time.
I spent about 150-200 hours on the three parts, about 12-15 hours a week, starting October 16th of 2 consecutive years.
Did part 1 by Xmas and part 3 by Jan 31st before tax season kicked off. Took part 2 by Xmas the following year.
I think it was roughly 70 hours part 1, 80 part 2, and 40-60ish for part 3, I have the logs somewhere. I did the full Gleim method which was time consuming. If I did it again I would trim certain areas of study to accelerate the course. I was overprepared.
I spend 550 hours over 5.5 months for the CPA exams with 92 avg score to put it in perspective.