first off you should get a factory service manual and a clymer/haynes repair manual, as 1 or both will have a wiring diagram which will answer most of these questions. second, if your bike is similar to mine (which is a 500T) your headlight, taillight, and front turn signals should all be on when the bike is on and the headlight switch is in the lo-beam setting. when in high beam the front turn signals will not be on, though. third, the taillight is the brake light. it will get brighter when the brakes are applied. so, you're probably right about something being crossed. so, get some manuals, pop open the junction box (behind the headtube and below the tank) and make sure everything is wired correctly. my guess is that it's not. good luck.