There is no limit to who many wires may be distributed from your booster. The 30ft (10m) guideline is for the maximum length of any one wire.
You can distribute the power any way that meets your needs. You can solder them, use insulation displacement connectors, terminal strips, etc. For the helix at my local club, they separated the levels with threaded rod. They then applied the power to two of these rods. They used nuts and lugs to distribute the power from the rods to the tracks.
Wiring For DCC