1. You must wear a black suit, black shoes and a white dress shirt to court. You should also own a tie that is as black and as sober as you can find.
2. It's a pity that Iris is out of your budget. Isetan occasionally holds sales for Boss suits at their branch in Lido. Alternatively, get a cheap suit from any of the tailors you mentioned to tide you over until you can get something better.
3. I've had good experiences with Herring
Feel free to pm me.