Hi, Gayle
my husband's therapy machine went down more than once - scared me, too, but they always got it working again. The RO will have a plan for 'make up' sessions if it is needed. Missing a time or two is normal.

1. Cisplatin vs Carboplatin: don't know.
2. The mandibule: with a tonsil cancer, they are not concentrating the dose directly at the mandible - it's not going to get the full blast. There are problems with ORN as a late effect but its not a sure thing. My husband's RO emphasized that nutrition (not just calories) was important to rebuild tissue and bone.
3. Dental: go for the trays asap. He will need to get them made by taking an impression, and that may be too uncomfortable soon. He may need to take some time off from the trays as the radiation gets intense. The trays will be there for the long term.
4. Recommendations for other comforts:
a. moisturizers/lotions - aquaphor (by Eucerin) after the radiation session. Toward the end of the therapy, the RO switched him over to burn cream.
b. humidifiers - yes - we have a Honeywell Invisible mist. Also, the white noise helps ME sleep.
c. mouth wash - Biotene.
d. toothpaste - Biotene.

*** tooth brush ***
He will want a VERY soft one. I couldn't find one for adults ...so I got him a Sponge Bob one. Made him laugh.

e & f - don't know.

Other stuff:

'Magic Mouthwash" or "BMX" - get this before he needs it.

If (when) he goes on narcotic pain meds, don't let the constipation from them get out of hand.

Hugs back to you, Gayle.