Re: artillery advancing under fire
The best answer is for you to get a copy of Hunt-Barry-French's Instructions for Field Artillery manual and read it. It is readily available, and has explanations for crew drill, full of diagrams and is the authoritative source on artillery tactics. Also is Gibbon's Artillerists' manual, but it is more focused on tactics vice crew drill so it may apply to your question better.
24th Mo Vol Inf
Cannoneer, US Army FA Museum Gun Crew
Member, Oklahoma Civil War Sesquicentennial Commission
Company of Military Historians
Lawton/Fort Sill, OK
Pacifism is a shifty doctrine under which a man accepts the benefits of the social group without being willing to pay -- and claims a halo for his dishonesty.— Robert A. Heinlein