1. To access the bulb, just turn the bar to left/right deadlock position, reach down there to pull out the H4 plug, and then pull out the rubber cover, then undo the metal clip on the bulb, now the bulb is free. to install new led bulb, just do the reverse process.
2. Emitter need to be vertical, but most bulbs comes slighted tilted to get the best light pattern
3. rubber boot is your guard to prevent dust getting into the light housing, don't cut it, baby it
I currently have the most powerful LED H4 light installed on my bike, each bulb rated 45W, drawing 3.7Amp current, however, it is still not as good as the new projected headlights(such as on my wife's sienna), even not as strong as my led running light, which are CREE XHP70 chips and rated 18W each, projected. Projected light the way to go.