Iceland have only failed to score in 2 of their last 21 away games. That includes goals in Portugal, France and Belgium.
With that said, they haver recently lost while scoring against slightly tougher opposition in Belgium, Wales and Czech Republic. So when they play the better teams, they're usually good for a goal but don't usually get a good result. 10/1 is still generous, but I think the bookies might not actually be as far out as first thought.
Kazakhstan are obviously shit but they've scored (but lost) in Germany, Ireland, Netherlands and Turkey in the past couple of years. All 6 of Czech Republic's qualifying games have seen BTTS. The single is 8/5 alone.