I know you are worried and anxious now, but once you go to WDW using an ecv, you will be a veteran in no time.
Frankly, I don't care what
attitudes/stares I might run into. Let me put it another way. In my former, healthy life, I lived and worked like anyone else. I was raised to be polite and to see the sunny side of life. Even so, there were people critical of me or what I was doing. I eventually realized their complaints about me weren't really about me, but because they had an agenda, like to make you feel as bad as they feel, or criticize you personally because you have a better job and they don't. So I don't worry when other people say bad things. I just pity them for missing so much that is good.
Using an ecv and getting on rides depends on you. For example, on Jungle Cruise, you can park your ecv and get in the regular line, OR get in the handicap line with your ecv, then enter the boat by walking, OR there is ONE boat that will load your ecv if you can't manage two steps down into the boat. If I travel solo, I wait for the ecv-boat. But it is a long wait, as there is only one of these boats.
How many stares will you get from people. Honestly, who has time to look? I am busy driving my
scooter, listening to my loved ones, and looking around. So are other people. If it is really a worry, try some reverse psychology. You and your kids decorate your scooter with cheap glow in the dark stars that you tape on, etc. Print out small pictures of Disney characters and tape them on. (Buy a small bottle of rubbing alcohol or Goo Gone to eradicate tape residue.) Buy cheap bunches of glow in the dark bracelets and necklaces and loop them over your handlebars, then give them out one by one as other kids notice them when it gets dark. Play up some theme like your own personal Doom Buggy, or your own Cinderella's Pumpkin carriage. You can get a string of solar lights at Target or online and string it around the scooter and keep the solar charger in your front basket. You could be the center of COOL in your kids' eyes!
Riding ecv onto/off the monorail. Only scary the first time, then you will see it is no problem. Aim straight, go medium speed. Stop before you hit the wall on other side. If you do hit the wall on other side, kids will laugh, so will you. That's about it. Backing out: Aim straight, don't turn head because this tends to make you turn your wheel. Easy does it. CM will assist you from behind. Don't go until CM has put the ramp up. Really, this has happened.
Get those cheap rain ponchos at Wal-mart. Get a bunch -- they rip. Also bring some plastic grocery bags. If it looks like rain going into a ride, cover scooter controls on handle bar with bags. Put poncho over scooter seat.
Remember, you are under no obligation to answer other people's questions about why you are on an ecv. Just smile and enjoy your trip. Let us hear from you when you get back!