Where to buy hardwood for drawer rails and dowel spacing

[ToolbeltDandy]

I'm designing a bookcase which I will build from PSE redwood. I would like some advice regarding the drawer rails and the spacing of dowels.

I need some short lengths of hardwood to serve as drawer rails (I've read that softwood on softwood is a bad idea) but neither B&Q nor Wickes appear to stock anything suitable (according to their websites).

Also, how far apart should my dowels be?

Should I use dowel pins for all the joints or would it be better to use screws?

Here is an unfinished scale drawing of my design; you can see that I'm using four 69mm x 69 mm posts and many 18 mm x 119 mm boards:

I've never designed furniture before and I'm pretty new to woodworking, so I expect to learn a lot from this project. I might also design an alternative version that replaces the drawers with a cupboard and build that instead.

 

[big-all]

any timber over 6x1" should be l
made up from laminated boards with alternating boards[grain up grain down

the base and the back would normaly be 6mm ply rebated into the frame

use softwood for the runners they will last fine providing you use 2x1 par
whatever height the drawer sides are just space the runners 4 to 6mm further apart and they will easily last several years