4 short questions about formations

1. are there still illegale formations?
2. is it sometimes useful to play mixed passes (long +short, middle and flanks)?
3. is it useful to focus the weaker flank of the enemy and do offensive arrows on that flank and passiv arrows on the other?
4. are asymetric formations useful?
f.e. 1. (3n - 2dmc + dml - mc ml - aml - st) playing only left flank
2. (4 - 1 - 3w - 2) but the dmc is on the right central spot and the mc on the left central spot. ... kinda 4- 4 - 2 but the one mc is put behind in dmc.
a bit more offensive left an right a bit more defensive.
3. 3dc+dr - dmc+ dml - 2 mc - amr + amc (instead of central on the right spot of the amc'-positions + st but on the left spot)

hope you know what my examples mean. if not i will open another thread an post screenshots:)