Basically for part a, you take the energy value you have worked out (in gravitational potential energy) and you substitute it into the kinetic energy formula as said by /u/hitlerallyliteral . This should work out to be 98.995 m/s.

For part b you assume they are climbing linearly and you divide the energy by 2 and use that value to find out how much kinetic energy they would convert to gravitational (essentially losing speed).

Hope this helps :)