Lets see
I got the PEG after the first or second Rad treatment (24th of May). At that point there were no effect from the radiation. It was taken out in August, once it was clear that I could eat enough normally. I would not worry about PEG tube addiction, I cannot imagine how one gets addicted to the thing. Pain medication, is a different story.
It is best if you do not throw up. The medication/chemo makes you nauseous but there are drugs to hopefully avoid this, this is something to prepare for (your mouth is really sensitive).
Re small amount of chemo. I am not sure what this exactly means. From what I gather you are getting radiation with concurrent chemo. There are generally two ways of doing this. Big amounts of (cisplatin or carboplatin)** typically 3 times, or alternatively, weekly. If you get this weekly the dose is lower (see my signature) and the drug is better tolerated. The point of concurrent chemo is to sensitize the cancer cells and thereby enhance the effect of the radiation and also to provide some protection against cancer cells that may have migrated or are about to do so. I think this is what he MAY have meant but you want to check on this! In order for chemo to be useful you cannot just take a little bit.

** You could also be getting other chemo drugs such as 5FU etc or something like Erbitux.

Hope this helps