I am by no means an expert, but I'll have a stab at this. Japan in written in katakana because it is an English word. The Japanese do not, and never have as far as I know, used the word Japan to refer to their own country. I believe the word Japan is a corruption of what the Chinese used to call Japan hundreds of years ago, which in turn is probably a corruption of what the Japanese referred to themselves as at that time (which may be different to the word they use now.)
I think you are also right in saying that in this particular context, the reason they use the word ジャパン and not 日本 is because it is part of the name of the company, BSジャパン - Japan Broadcasting [Station?] (You missed out the BS).
As for a translation, it is something like this:
BSジャパン have made a broadcasting decision !
It will be broadcast starting from Sunday 14 January, every week on Sundays at 11:30!!
As for what is being broadcast, I have no idea - presumably this was apparent from the context of the original post.
Hope that helps