However, the coolant level in the reservoir is about 2mm below the Low line so minimally a top up is required.
If the coolant has never been changed then you know its OEM coolant so you could top it off with that. On the other hand, if the hoses were leaking then someone has probably touched the radiator/hoses in its recent past.
If you don't know what is in it and its such a small amount a one time top off with distilled water would be compatible with any type of coolant and not hurt anything. It would dilute the additives a tiny amount (for lubing the water pump) and it would raise the freezing point a bit but I'd think its a pretty insignificant change unless you are riding in Alaska or Siberia. In any case, it would buy you time to do the full flush.
In reading around the site, it appears that bad things could happen if I simply add a coolant of my choosing to the unknown coolant in the system. Since, to my knowledge, the bike has never had the coolant replaced, I believe the best course of action is to replace the lot.
As far as I know, it is true that mixing some kinds of coolant can be bad but I don't know the details. I change my coolant every 2-3 years. It is very common to change it when buying a used bike just for peace of mind.
I have purchased some Engine Ice (on recommendation from a work colleague, looking around this site and the fact that it is not toxic to pets) and plan to take the following approach (as per the recommendations on the Engine Ice website):
1. Drain existing coolant
2. Flush with 50/50 distilled water/vinegar mixture
3. Flush with distilled water
4. Refill cooling system
After each filling I would start the bike and let it idle until the fan comes on to ensure that the fluid is circulated.
Yeah, Engine Ice is not necessary. I'd just do a site search here for Antifreeze or Coolant and read the discussions and make a choice. I use Zerex Asian but any major brand compatible with aluminum engines/radiators and silicate free will work fine.
My questions are this:
1. How long do the cooling system hoses typically last?
I'd say about 10 years give or take would be the max I'd run them. On my 2007 I replaced mine in its 7th year at 80K miles and they looked fine. I had it apart for other work so took the opportunity to do the hoses, thermostat, o-rings, etc. but also I'd hate to get stranded on the road due to a busted radiator hose. I replace batteries at 5 years to avoid a breakdown too.
Since I am going to all this effort and they are over 4 years old, there is an opportunity to replace, however, they are expensive and if they typically last, say 10 years, then I will wait. Are there any other cooling system components that degrade over time that I should consider replacing while I have the bike apart?
Not really, as long as you flush every 2-3 years you are a long ways from needing to replace the cooling system parts.
2. Is a single distilled water flush following the vinegar sufficient to get rid of the vinegar? How much fluid remains in the cooling system when it is drained?
When I shut down my (new-to-me used) bike for major service I had no idea what was in the system. I flushed it with two gallons of distilled water then added the Zerex Asian. I have not heard about a vinegar flush but I assume that's to treat corrosion. Your bike is so new I would not even bother with a vinegar flush. I'd flush it with distilled water and fill it with your antifreeze of choice and go ride.