Can fruits and vegetables be eaten at the same time when juicing for maximunm nutritional results?

Yes. Why wouldn't they?

Don't rely on juicing exclusively unless you have a pressing medical/dental need to not use your jaw. You need to chew food too. Your saliva contains enzymes that break down foods in ways that juicing doesn't.

Yes, you can combine and consuming fresh juice is the best way to give the immune system a boost!