Ka-26 answer
First of all sorry for my English, guys, I'm from Russia (hopefully your Russian is just a little better than my English :-)) Someone here asked about autorotation on Ka-26 helicopters. I have some hours (around 3000) in this helicopter and have done quite a few autorotations. The pedals work the same way, no difference from the conventional helicopters. Everything works the same way.
The advantages of co-axial machines are: short tail boom, so no worries in confined areas; no worries where is the wind from - right or left; no extra power for the tail rotor, so all power is used in the main rotors; etc...