On 26/04/2017 15:15, Stephen wrote:

Do I need to 2x2 at all, as I have seen some beds where the ends have
been butted together and just screwed through.

I don't know the answer to your other questions, but I have used
decking, and I wouldn't attempt to screw into the end grain. You might
get away with it, particularly if you put glue in the holes.