how fun a universal and disney trip together. I can not speck for universal ( it has been a number of years like 20 to 25 years since I have been( but as fair as disney they have done a really good job at making lines assessable to all people most you will enter the line that you need like stand by or FP ( if you have a FP)
a few lines when you get to the boarding area or close to it you may be asked to go in another area this is either because of 2 things there are steps in the line ( splash at MK and toy story at HS are 2 of these) or there is not much room in the lead area or they have you go to the exit 7DMT and buzz are two like this.
there are even fewer that you will have an alternative entrance where you will basically go through the exit
BTMRR, JC, IASW, and space ship earth are the ones I can think of.
This rides if the wait is longer then 10 minutes you will get a return time to come back latter.
I would either pick up a disability guide so you can have an idea of what to do for each ride ( some you can not take your
ECV in the lines, or ask the CM at the ride entrance ( and chases are they will let you know what to do when they see you coming exspasily if you can not take your ECV or if you need to do something different
have a great trip and remember after you use your first 3 FP you can book one more on your phone or at the kiosk that are brought out the park.