Question regarding buying and switching weapons

I have some question on weapons and their use and how you pay for them:

• For example in the WotR lists, a Knight comes with a melee weapon.
  What is a melee weapon? Is it a sword? The notes below suggest that they have a sword which they can drop for a 5pts refund.
  
• Is a 2 handed weapon really for free? There is no point cost for it.
  
• I couldn't find any rule on switching melee weapons, can you switch them as you want when you have more than one? Is there any prerequisite such as winning a melee, having no enemy in a certain range or something like that? Otherwise I cannot see the point of having more than one melee weapon.
  
• Giving Billmen a dagger is solely for WYSIWYG reasons? The polearm is always better or does the "building rule" apply to polearms, too?
  

sorry for not notocing this post before.

Melee weapons was intended to be a sword. There is a typo. Also a 2 handed sword cost 8pts extra. Please see the same list but at the mounted version.

Switching weapons takes one action (it is same as par. 6.6)

A second melee weapon is in most cases useless, with few exception for fighting in houses and for some campaign/role playing/scenario games.
Also a weapon can be captured so a second weapon can be helpful in that case.
Bills should not be penalized by fighting in houses but can be decided otherwise.

Skirmishers have the option to buy daggers. They don't have any weapon close combat weapon listed if armed with bow or crossbow. Does that mean they have to use their fists in close combat (if charged and failed to evade) and can't charge on their own? How many dice do they get if fighting without weapons?

they can charge and they can use fists or any occasional stuff they have in hands. Also a crossbow can be used for the scope. The "melee weapon" is just an upgrade to their melee capability that is C. A melee weapon gives re-roll or some other advantages but it is not necessary to have a melee. Consider them just an extra ability.

Ok, thank you. In all occasions we had it was knights charging down those poor skirmishers so it didn't make any difference.