Regarding the corrosion...may I ask if the vent tube was hooked up properly on the positive post side of the battery (especially if you're using a wet cell lead/acid battery)? If not, that may be the reason for the excessive corrosion.
You can see the vehicle's gray vent tube attached to the left side of the battery in the pic below:
I'm not sure if or how to go around the BST (battery safety terminal) because it keeps the high amp and regular fuses attached to the battery and powered but disconnects the engine bay from the battery to help prevent fires in an accident. If (God forbid) you are in an accident...the BST disconnects power to the engine bay...but leaves power for the doors to unlock, interior lights to come on, and emergency flashers to operate: