I suppose it took days for the media to report the friendly fire possibility. I imagine the authorities were waiting for the officer that was shot to become stable. I believe they were hoping to retrieve the bullet, which unfortunately they could not. Five days does not seem long when the first priority is the saving the officer's life. You can hypothesize that it was friendly fire, but you need forensics to verify it.
I believe, from the way the officers described it in this interview, (
http://tv.msnbc.com/2013/05/14/watertown-police-officers-how-the-tsarnaev-firefight-went-down/) Officer D. was hit when they were shooting at DT as he was running over his brother and fleeing the scene.
Regarding the "a mind dumbing amount of shooting going on at a suspect that is trapped in a boat", you are correct. There were a lot of shots at DT. They used rubber bullets and flash bombs intentionally to get him to come out alive. I heard it discussed on the police scanner as it was happening. They wanted a live DT so they could get answers from him. Keep in mind they still did not know DT was unarmed and I am sure they were prepared to use real bullets but their first goal was to disorient DT and then have a negotiator talk him out of the boat.
As for Orlando, there are many unknowns at this point. I have not seen it stated anywhere that they do not have a recording. I just don't think any information is being given out right now. Perhaps its because they do not have a "person in custody" (IT is dead) and the evidence they have may implicate a suspect they do have in custody (DT). I am waiting for more information before judging their actions.