Honda says to change the timing belt every 7 years or 105,000 miles.
I wouldn't assume it's been replaced. It is possible for a mechanic to pry back the cover and look at the belt. By doing this, they can usually tell if it's a replacement belt. If it looks original or worn, change it!
The tensioners normally aren't replaced along with the timing belts because they rarely go bad on Hondas. It is a smart thing to replace the water pump, seals and the other belts while they are " in there".
I think you may need to find a more competant mechanic. They should be able to hoke up a scanner to see what is causing that light to come on. Smelling a "strong smell" of gas is never a good thing and you shouldn't ignore this. It could be something as simple as a bad gas cap.
I alos need to stress the need to find a shop that knows Hondas inside and out and not a shop that guesses at problems.
Those are VERY reliable cars that can go 300,000 miles and more IF they are taken care of.