I don't "spider rig", per se, as I mostly Push jigs. But let's just say that "if I were to start trying it", the answers to your questions would be :
Favorite setup = 1/2 to 3/4oz weight above a leader line to a single jig
Jig size = variable between 1/32oz & 1/8oz (with at least a #4 Aberdeen hook, but prefer a #2 - esp. using separate plastics)
Speed = no greater than 0.5mph (I consider anything over 0.5mph as Pushing speeds)
And regardless of what type of jig I was using ... it would likely be tipped with a minner. (which is another distinction, I believe, between Spider Rigging & Pushing ... as no live offerings are usually used when Pushing)