[CivvyCivvy]

I am in the throws of revamping our home-brew WW1 Aerial Wargames Rules, and a query has arisen regarding the firing of the Lewis and Vickers guns on the SE5a (and some Camels for that matter). Please bear with me and I'll try to explain.
Being drum fed, the Lewis is given four shots per drum. Each move, an aircraft can fire up to three bursts. So, in theory, the Se5 can fire three bursts, from two guns per turn. Likewise, an Albatross can fire three bursts from two guns per turn.
Now the complications. The Vickers is given a minus one factor for its slower rate of fire. The Albatross will receive a plus one factor for two guns firing. These factors are used on the die rolls assessing the damage done by the guns.
If say, a two gun (Vickers) Camel fired, it would receive both factors, therefore cancelling each other out.
Are you still with me?
So if the SE5a fires both its guns at the same time, should it receive the plus one factor for two guns firing, and/or the minus one factor for slower rate of fire. They cannot be fired (diced for) independently, as you would then have possibly twice the amount of damage (up to six bursts, three from each gun, as against up three bursts of two guns from the Albatross).
So, I suppose my questions are, what was the rate of fire for the Lewis Gun, the Vickers and the Spandau (excuse my ignorance). Did the French use British weaponry, or if not, what were their rates of fire.
And another thing. Did having a Lewis or Vickers installed on Nieuport 17, affect its flying abilities in any way?
I thank for your patience, and eagerly await any responses.