1) Wpf does count, the higher your wpf, less upkeep you pay, I don't know of the point where it comes "base" however.
2) It would count as 1 handed afaik.
3) Ranged weapons don't have increased upkeep, longbow upkeep is 777 which is 7% of the buy price. Wpf does effect these.
4) They do not.
5) Yes they do.
The gereral upkeep percentage is 7%. To be honest, I don't notice the wpf change for upkeep and I believe there was something said about arrows that meant that they have an increased upkeep.
Generally, I just got by the 7% rule. RoundUp(Base_Price * 0.07) and that'll give you your answer effectively.