Strategy

Personally, I think it would be best to split up any Ronin who join our ranks.  That way the chance of them revolting is less.  Also I think that Sparrow's who have completed their Gempukku ceremony be given preference as far as leadership positions go.  While experienced Ronin might be able to command small groups, I think the majority of the command should be in Sparrow Bushi hands.

Also I think that Sparrow clan's Vindicators should wear no flags.  They will only wear the Sparrow mon on their uniform.  This will distinguish them from other units.  A simple uniform is best.  Also they should be kept from Sparrow lands for example sent to stationed to guard other clans lands.  Only once they have proven there loyalty to the clan should they be allowed on Sparrow lands.  I think the Vindicators should train defending the Kaiu wall.
Perhaps after they have proven themselves, they can be stationed elsewhere.  For example, perhaps Sparrows should train with the monks of Shinden Osano-Wan.  Then the Sparrows can help to care for the temple, and defend it if necessary.  Perhaps the monks and Sparrows could exchange fighting techniques.

It would be better for the Sparrow to operate in small numbers spread out rather then a concentrated force.  As such a force would require more food.  Also if a few groups of Sparrow were taken out, the rest would still be around.  However, if they were all in one place and the entire force could be eliminated.

Once a Sparrow graduates there Gempukku, they could be put in charge of a group of small ronin.  Then they could be sent out to do service in another land.  That way, the ronin would act as a force multiply for the Sparrow.  Eventually, the Ronin could be adopted into the Sparrow clan.