With Rice it is fairly simple to reheat. They can just throw it in a pan with just a touch more liquid and "stirfry" it until it comes up to temperature. It doesn't take very long for rice to reheat.
Risotto is also easy. Since you want that gooey cheesy consistency anyway, have them out it in a frying pan and add 1/4 chicken broth to it, stirring until it come up to temperature.
Pasta - that's the tricky one. Parboiling it is one way to do it (that's pretty much the way they do it in those Bertolli frozen dinners). But the family has to really keep ane eye on it. Perhaps it would be best for you to experiment with it at hime yourslef to decide which way is best, before you send it out to your clients.
Also, there is a website:
American Personal & Private Chef Association I did an interview with the woman who runs it a looooong time ago. I think you have to join it to get all the perks, but they have tips on how to prepare things. Most of their stuff is business oriented though. There are many persaonl chef sites on line that might have good advice for yout, too.
Good Luck!