Hi John, welcome to the forum
. I see no ones answered your questions yet but I've got a question for you - I'm not sure what you mean by water logging? Is this where the siphon doesn't break and the water level gets too high?
1. You don't need to use a siphon -"Constant Flood" systems are almost identical to Siphon based Flood and Drain systems but they have no weep hole in the standpipe and they don't have a bell siphon over the standpipe. The water runs all the time with the beds flooded to just below the surface (depth set by the standpipe). The goal being to keep the surface dry with the media below wet in order to provide filtration. The water is oxygenated by the constant movement. In the event of a power failure the water stays in the grow bed.
2. The standpipe must be able to drain the water as fast as it comes in. The fill rates should be closer if the delivery pipes are below the risers so that the main pipe fills first and then delivers the flow to the grow beds but if you just use large enough drain pipes and CF you won't need to be concerned about this. If you stick with siphons you might have to add ball valves to regulate the flow (in some cases you can also use elbows that aren't glued so you can rotate them)
You may want to post up a design and see what people say before you build
Sorry it took so long to get the answers and hope this is what you were looking for.