Question 1: Find out what the objectives are. Do they want to have fun? Do they want to lose weight? Do they want to train? Do they want to compete (whatever sport they are doing). So goals and objectives ARE the main thing to find out. (Remember:) if you don't think you can do it, or don't have time. Say it straight out. Don't keep them waiting for the incase. As well if you find you are struggling don't be shy to ask the athlete of the parents (if minor) about it. They will be happy to answer.
Question 2: Time and Strengths. Knowing the athletes time and strengths before starting is essential. What one can do might not be the case of any of your other athletes, whether or not they are both healthy or suffer the same chronic illness. Nobody is the same. But what you have to know is especially one with these illnesses...is there will always be good and bad days. Some days an athlete can do 20 mins and be in excruciating pain...while other days the athlete can be in top shape and do 3 hours and you wouldn't even know anything is wrong.
I have some templates that will be posted later on to further develop an athlete. I am still doing it as a trial and error but believe me it helps especially mentally.
But as I am saying: you should be okay with the scheduling and be understanding. It is not their fault. And yes for team sports it could be even tougher. But communication is key in this case. Ask how they feel after every shift. Listen to them and trust their instincts.
Finally remember to have fun. Athletes learn better when fun is involved (keep discipline too). Don't constantly yell or push it'll just make things worse. All we want is to feel normal even when our bodies do not allow us too.