Is it worth bring down some bicycles to ride in the park?

If you are camping, yes!!

The trails to the beach by the ( camping area) yes beach area no :)

What park there's no park in there only a camping site and the beacg

There is also a road that brings you up to the back of the pavilion that's closed to cars. It starts in the north west corner of the parking area.

And it can get a little muddy

Yes

Yes lots of room to ride but not on beach