2. I'm thinking a good strategy could be to put a military sb in a location where its ring encompasses the mining sb, and perhaps a planet or two if possible. Then build the ship assist modules. When the enemy comes to attack planets or the mining sb - the military sb would help the battle - even though its taking place at the very outermost part of the 'ring' right.
The Influence ring that you see on the map screen is not specfically the 'area of effect' of an SB's special purpose.
It is the area that is brought under your Influence by the presence of a SB. Althought the degree of influence within a SB influence area can be incresed, by racial bonuses and Civ-wide influence resource mining, and
for Influence SBs by specific influence enhancing modules, the area covered by SB influence never grows. You can see this clearly sometimes when the Super-Influence random event strikes. Planet influence boundaries expand dramatically over a couple of turns, SB influence rings (that aren't temporarily swallowed up) don't change.
The SB 'area of effect' for its special purpose (military assist, production & trade boost, or influence boost) is
approximated by the shaded area and animated dotted line that appears when you select (left-click) the base. The intended radius of that 'area of effect' is 8 parsecs. In practical terms, the area that will be affected is better stated as 'a pattern of squares that are
touched by a circle around the SB 8 parsecs in radius.' If a square is just 'nicked' by that dotted circle, it gets the benefit.
drrider