The first time I saw Bolt was in Kingston 2002, when, only 16, he won World Junior Championships running in 20"58 his semi and 20"61 the final, destroying athletes 3 years older. His training was very poor, like a normal student in a school.
I remember that, looking at him, I said "this will be the future WR holder of 200 and 400m".
Next year he won World Youth Championships running the current WY record of 20"13, and ran 400m in 45"35 with no preparation about any kind of endurance.
In 2004, not yet 18, ran for the first time under 20", with the current WJR of 19"93, still with very little training.
In 2006, finally... he started to train !
So, when I see that Tyson Gay, for example, was far from him 1 and half meter only, I have to think that of course the second has to use PEDs for arriving so close, because the talent of Bolt is something never seen before (for 200m), superior to Tommy Smith too, and he was able to turn his talent from 400m (if really interested in this distance, probably the WR could be 42"50 today) to 100m (the FASTEST man in the world is something more fascinating).
So, I don't care about the lack of antidoping control for Bolt : this could be a problem for other athletes, not for him, who didn't need any external aid for reaching levels not allowed to any other sprinter, in the past and in the present.
About your last question : I think both of them could run around 49". Kenenisa, for his muscle strength and the ability to have a superior frequency, was of sure fastest in 100m, also connected with a long practice as football (soccer) player when was very young, and was able to have quick change of speed, like Mo couldn't have, due his running technique, very elastic, very relaxed, but with too long strides for quickly changing speed.
Anyway, don't consider his 12"9 in a fake competition organized in some TV program as something real : the best athlete in the world, out of season, of sure doesn't risk to face some injury for an easy exhibition without any technical clue. In that occasion, Mo ran a normal progressive strike, without any type of effort, with the only goal to finish fit.
Mo was with me for about 10 months in Kenya, and with me he started to do short sprints on hills, and more long fast run. When already was with Alberto, but in training in Iten, he ran, during a full period of preparation for long distances, one 200m on a dirty track of Iten in 23"8 (I was the timekeeper).
About Kenenisa, he ran the first turn of his last lap in Golden Gala 2006 in Rome in 12"1, so in my opinion could run under 11" in 100m without start. I think he was also a little bit stronger than Mo in 1500m (don't look at his PB : was in Shanghai, at the end of a season, already relaxed and with little training, for attracting local spectators only), while Mo could be faster in 800m, due to the different extension of his strides.