Hi, I'm about to connect two carcases of my writing desk together to finish the final desk assembly. The two stacks of drawers are attached by a 4" wide apron at the back that I intend to join to the rear inside legs with dominos. Since the leg grain runs vertically and the apron grain runs horizontally, I have a cross grain situation (not unexpected). I have been intending to join the apron to the legs with multiple dominos, but I have two questions:

1. How many dominos should I use? this is an eight-legged writing desk, so the primary resistance to racking between the two stacks of drawers. The top will be a frame and panel design (the panels will be leather insets), so the desk top itself will provide some assistance, but the 4" apron provides the most resistance to racking...

2. Do I need to be worried about expansion/contraction in the multiple domino cross grain connection given the relatively small width of the apron? All parts are cherry...

The desk kneehole at the front will contain a fall front keyboard drawer. I've decided to join the drawer assemblies together on the front with a drawer frame of ¾ stock. The drawer opening will be approximately 4". I'm intending to join the bottom of the keyboard drawer frame to the drawer assemblies with dominos, 1 per. But for the top, show I instead cut a dovetail or double dovetail joint due to the proximity of the domino to the top of the leg and the small amount of short grain on the leg above what would be the mortice of the domino?

Thanks for your suggestions.

Mike