Hi-- i think it's all pretty normal.
Most people wait about a month to begin treatment.
Temozolomide with radiation is the std of care now for brain tumor patients. Your Dad will continue that at a stronger dosage when he's done with RX-- as long as his blood counts are alright. So it's important that you do everything you can do boost the immune system. I'd suggest looking into some suppliments that do that.
If he's not responding well and there's still growth with temezolomide then you'll try something else-- another chemo drug-- there are several out there-- pick ones that are common-- i'd stay away from 'trials' you don't want to become anyones experiment.
I would suggest trials though if it's alternative treatments to be taken in conjunction with chemo. Remember-- these suckers are VERY aggressive-- so you've got to hit them with all you can.
I would suggest visiting the "DCA site" it's an old drug that's being used to treat cancer off-label.
Good luck and remember take time to make your decisions.