Boru, you asked for an army build. I am not the best on land but this is what I did/do. At lower ranks (1-3 or 4), I used 3-5 yari cav with the remainder being sword inf (load sword or katana sams) and archers. As a lower ranked player, there is one advantage. When I play a 1 - 2 ranked player (as a rank 10) my gen cost so much that I have a problem building an army. My biggest problem is someone who buys a lot of yari cav. From rank 5 up, I would utilize the clan retainer and use sword bonus producing retainers. I use a combo of cook (-2 enemy melee inf), blade master (+3 sword inf), sword instructor (+2 sword inf), shogun emissary (allows great guard), and clan retainer. I use 4 to 5 katana and no duch sams (majority vets) in each battle. I have some katana sams with attack rating of 29 and I am now upgrading their charge bonus. So, I would concentrate on building an army of vet sword inf, great guard, a few vet yari cav, maybe 2 monk matchlocks and archers.
This is just an outline of what seems to work for me best. Since the patch, edged weapons have become more effective.