You are trying to follow the letter of the law. Unfortunately, i think even if you had the neccessary permits you would still be harassed if you are at the wrong place at the wrong time,since the ones enforcing the law dont respect it themselves. So you are perhaps better of taking a chance and not getting any permits just walking around taking pictures.

I used to do photo walks with friends (http://www.flickr.com/groups/nairobistreetshooters ) we have never actually been harassed ; but with the  post terrorism paranoia epidemic going around, i think walking around with a camera in town maybe  a bad idea.