M_Boats: cleaning my M15

Hi all, I am cleaning up the M15 I purchased last fall and was wondering... I found a bunch of loose styrofoam (sp?) like that used to pack tv or stereo etc. in the forward area under the v-berth (I'm too much of a newbie to know the proper term, sorry). Is this for floatation? Is it necessary? I pulled it out because it stinks. I would replace it if that is the consensus. Also, I am puzzled as to how any water that happened to get below would drain. Is there some way out? I kind of want to just hose everything down in there but maybe that's not such a good idea. My M15 is #500 made in 1992 if that is of any help. thanks - Dan