Alex, I hope you don't mind hopping on your P&M thread with some questions of my own.

I've started today with a Spanish campaign in the age of exploration setting (early game). This is actually a restart of my abandoned first P&M game (so this will be my second try).
I've started with a turtle/teching up strategy. I planned to go on the offensive once I get an army of good units. First I took out the Muslim rebels in Grenada and bribed the last survivers once it became clear I had to storm the citadel to get the province. I've bribed myself in possession of Morocco, Algeria and Malta and have connected them at last with my ships. Malta revolted but was easily put down without reïnforcements. Then Navarra attacked just when I finally came close to producing a decent army. BTW I repelled them easily enough, I didn't expect my rodeleros to be able to stand up against landsknecht-halbards and landsknecht-pikemen but they did admirably (My missile troops were also responsable for the victory).

Now my questions:

1. I haven't played much MTW in late so I have little to no experience with cannons but I didn't expect serpentines to be so weak. I had 2 serpentine crews set up so they always had a clear shot. They both had a valour of 2 and they always shot at the most bunched up group of units. They shot until they were out of ammo but only killed 12 and 14 enemies. With this experience in mind they aren't worth fielding. Am I doing something wrong with them? What cannons are worth fielding?

2. The Province of Vallencia (?) is famous for its arbuceros but I can't research the needed technology there (arqebus -> caracol -> tertio). Is this a bug or are there some rules I'm not aware of?