In IN, you cannot chose to NOT call allies. Also, Patron of Arts is one of the best IN decisions => +2 prestige yearly*(cultural tradition is in HTTT so no cultural tradition in IN)? you joke? And the super uber events?
Well... it is impossible that you gain less from more merchant unless the trade centre vaules change. There might be a big war before - and it made iron prices higher, and now it ended so you gain less. Also did you lost any merchants from cot's? If so - you got an answer. This is just so, that prices of some things fluctuate, new cot's might appear.