Will these rules be flexible in their basing as say,Black Powder,where really only the formation depiction is the important bit,with the Formation foot print and number of figures not really all that important?
They are pretty flexible. I've successfully used the following infantry bases (in 15mm).
8 figures: 40mm x 30mm (2 deep) - (standard base)
6 figures: 30mm x 30mm (2 deep)
4 figures: 20mmx30mm (2 deep)
4 figures: 40mm x 15mm (1 deep)
3 figures: 30mm x 15mm (1 deep)
The basic 'tactical' area is 80mm x 60mm, which is 2x2 standard 8 figures bases or 3x2 6 figure bases. (90mm x 60mm). Any combination of the other bases can be used to create either 6 or 8 figure bases, which are then used to creat the tactical base.
Cavalry are used in a similar way, with:
3 figures: 40mm x 30mm (1 deep) - (standard base)
2 figures: 30mm x 30mm (1 deep)
The 'tactical' area is the same as for the infantry, and can be built by useing 4x3 figure bases or 6x2 figure bases.
Artillery are on the same width bases of 40mm or 30mm, with 40mm being the standard.
They are also formed into 'units' with the same frontage of the cavalry or infantry tactical area, but of course only 1 base deep. (so either 2 or 3 models to a 'unit')