Hi Wayne,
Some of the rides do have minimum height requirements. These particular attractions a child can not ride, even with an adult if they aren't tall enough (for safety reasons). To figure out which
attractions your little ones can ride, see this link:
HERE. You'll need to
select the Height arrow on the left and choose the different height criteria for
your little ones.
There will be many attractions that they can ride on with you. Some examples are: It's a Small World, The Many Adventures of Winnie the Pooh,
Pirates of the Caribbean, Peter Pan's Flight, Buzz Lightyear's Space Ranger Spin, Toy Story Mania, Kilimanjaro
Safari, Journey into Imagination, The Seas with Nemo and Friends, Spaceship
Earth and many more.
The park maps have an icon of a person with a
measuring stick next to them if the attraction has minimum height requirements.
This will make it easy for you to decide what they can ride.
You are definitely going to want a stroller(s) for the kids. The amount of walking involved in a average day at Disney could put a marathon runner to the test...let alone a little toddler. Do your back a favor, and have a stroller handy. The one time we chose not to bring one, my husband ended up giving piggy-back rides all day/night. When one kid got off, another would climb up on his shoulders. Poor guy. As far as whether to rent one or bring your own, that is really a matter of preference. The Disney strollers are hard, molded plastic (so not very comfy). They also can't leave the Parks. For that reason, when our children were younger, we always brought our own stroller so we could use it to get back to the room after a long day. You'll have to fold the stroller on the buses, but they don't have to be collapsed on the monorail.
Hope this helps and please let me know if you have further questions,
Kaylene