Do I understand that your ISIC card includes insurance coverage as you listed? If so, then it would appear that you already have travel insurance and are okay. READ THE POLICY CAREFULLY! And before you go, just to make sure there isn't any fine print (like you can only be repatriated home from your original destination, or Timbuktoo, or something...) Also, double check your US policy, just to be sure it'll cover you abroad. Finally, if you have a gold or platinum credit card, they sometimes also include travel insurance with their benefits, so double check to see if that's a player.
I would definitely advise travel insurance of some kind, especially for such a venture as a year long trip - there's plenty of opportunity to get sick in that long a journey - but it sounds like you're already in good shape. Also, regarding the hospital benefits, that $165/day isn't a whole heck of a lot, but in most places it's probably enough to cover an emergency room visit or short stay, as long as there isn't anything horribly wrong with you. Most countries with nationalized health programmes are a lot cheaper than the US.
Finally, is there any way you can extend your US health care plan to cover the remaining portion of your journey? That might be a cheaper alternative than the world nomad.
Sometimes when you have overlapping coverage (two policies covering the same risk, in this case, you!) there can be some argument (read, delay) over which company has the prime responsibility to pay, and which covers any shortfall, so it's not a bad idea to discuss the possibility of needing emergency cash with someone back home (a parent, usually), explaining that you DO have coverage and whatnot, but may need to pay up front and be reimbursed. It's just good to know this in advance, and makes the "I NEED MONEY NOW!" phone call a little less stressful, if they understand that it will be repaid!
Today's lesson in insurance and reinsurance has been brought to you by the letter K.
Sorry, my brief stint at a brokerage firm just reared it's ugly head...