The Beaufighter was developed using as many parts of the Beaufort which was a Torpedo Bomber.
Why Beau? I don't really know, but its often used as a short name for something good, attractive.
Miniguns didn't exist in WW2 so I suggest you stick to things that did exist. As for space the Beaufighter and Mossie both had more space than most, in particular the Mossie which had an internal bomb bay that could be used for extra.
Also if you want a reasoned debate suggest that you work out the weight of the Guns carried by the real planes and then propose alternatives within or close to that weight. Then they are realistic alternatives instead of flights of fantasy.