Hi

As a very novice DIY person I want to build a very simple platform bed,
and am struggling to find any advice online for something so simple.

My ultimate aim is to have a frame with four chunky, square legs
(around 15cm square). Mounted on these would be the 4 pieces of the
outer frame (2 running length, 2 running width).

So to my questions: in order to support a king size mattress, is any
wood suitable (strong enough) to simply lay on this outer frame, or
would slats be more appropriate. If so, would be it ok just to fix
these to the top of the outer frame, and what thickness wood should I
use? Should I consider anything running down the middle of the bed
(length or width) in order to add extra support to the slats?

Onto a more technical question, what joints should I use to fix the
frame onto the legs, the front and side frame timbers together, and
mounting the slats on or to the side of the frame?

Ideally the final construction would be easy to disassemble (for
removal) and also not creak at all