Bow and Arrow would be a good start for an EM. I have not played it for 35 years but was OK back then. I think I would like it a lot better now as I didn't quite understand it as a kid, goal wise but love the art work. Currently I do not own any Bally's, but I have considered a Hokus Pokus.
A 4 player EM will be a lot of work if it has not been fully shopped in 35+ years. I always go through my EM's completely and spend on a 4 player an easy 100+ hours into it. All those score wheels, steppers, and relay switches to clean/adjust and that's just the half of it! Then there is working on the Playfield and Backglass if needed.
Knowing your way around a schematic is a must but I did not know how to read one over a year ago and now it's all good, so you will learn too. I suggest you also always get the Owners manual with an EM purchase as it has more useful information about how the game works as well.
Once you get in with the EM crowd they can direct you to parts, etc. so generally not a problem unless you need a new/used Playfield and/or Backglass and even then some people reproduce them.
Prices depend on if you want a project pin or a collectors. I have bought an EM for as little as $100.00 but they will be totally beat, but a great full on project. A rare EM in excellent condition could run you thousands of dollars. Middle of the road pins about $500.00 to $800.00 in good shape for average titles. Just like your DMD's, what's your budget and the quality you are looking for will dictate what you will want to get.
Not sure on the weight differences but someone else said it was about the same as a DMD pin.
Note: There is no Test Button to push on EM's like on a DMD as YOU are the test button!
Also, we now have a new EM sub-forum on Pinside so I suggest you start posting there for EM related topics to help that sub-forum thrive.
Ken