Should I use dedicated trays for toning solutions, or is it okay to use trays I am using for processing such as fixer trays and just rinse/clean them thoroughly ?
In an ideal world you would use dedicated trays. But it's not essential. I use all my trays interchangeably, just be careful about cleaning (rinsing) them.
Rinsing after use is obvious, I usually give the tray a quick rinse before using it too, as a precaution.