1. I would recommend using Redstone Energy Conduits instead. They are a bit harder to build, but can not overload and will not accept power if none is needed.
2. I think rednet conduit is nicer on the lag. Personally I use ComputerCraft and wireless modems to turn on and off different parts with no need for lines. But that requires some programming.
As for the solar panels I don't know. I don't think they will do anything if the battery they charge is full.
For transformers I'd imagine it would be best to cut them off on the side that receives power to make sure as much as possible of the network is cut away.
3. I don't know anything about microblocks.
For lag reduction... no loops in IC2 power lines, reduce amount of pipes as much as possible (ME storage system I think is pretty humane to the server). Use liquiducts for liquid transfer. Minimize amount of redstone used. Avoid having machines turn on and off frequently (like every second). Reduce amount of animals you own. Avoid growing too many trees (growing trees and especially decaying leafs seems to lag a lot from my experience). I'm sure there are more things to think of as well