a few questions about melee.

1. why aren't dodge and parry an opposed test vs WS of the attacker?

2. can you dodge one attack and then parry a second in the same turn or is it if you do one the other is denied to you for that turn?

3. On other threads i have heard argument that parrying with a sheild does not incure the off hand penalties and that does not make sense to me. The cordination required to be activly parrying with one hand and attacking with the other seems to denote that it should indeed require two weapon fighting and ambidexterity.

4. does the gunslinger talent apply to two weapon melee or just ranged and if just ranged what does the same for melee?

1. why aren't dodge and parry an opposed test vs WS of the attacker?

Because your generic attack shouldn't be that hard to parry/dodge.
If you're worried about your enemy's ability to evade attacks, spend a half action on Feint, which lets you make an opposed WS test vs the defender - if you win it, he can't parry or dodge your next attack. So the mechanic is already there, but you have to spend a little extra on it, making it either/or compared to your standard Lightning Attack guy.

2. can you dodge one attack and then parry a second in the same turn or is it if you do one the other is denied to you for that turn?

No. You have one action of the type Full Action (can be split into two Half Actions) and one action of the type Reaction per round. Making a Parry or Dodge takes up one Reaction, so just like you can't fire a full auto burst (Full Action) and then run some more (another Full Action), you can't Parry (Reaction) and then Dodge (also a Reaction). The exception to that are the talents Wall of Steel and Step Aside, which grant additional Reaction type actions which can be used for parrying or dodging respectively.

3. On other threads i have heard argument that parrying with a sheild does not incure the off hand penalties and that does not make sense to me. The cordination required to be activly parrying with one hand and attacking with the other seems to denote that it should indeed require two weapon fighting and ambidexterity.

There are two reasons: Firstly, real world experience - believe me, parrying with one hand and attacking with the other is vastly easier than "true" two-weapon-fighting. Secondly, balance: If you wield a sword, you already are at +10 to parry and still have a free second hand. A shield gives you another +5 in exchange for that hand. Considering what else you could do with a free hand in combat, that's not exactly an unfair trade-off right there, but requiring additional talents would likely make it useless/too expensive for what you actually get.

4. does the gunslinger talent apply to two weapon melee or just ranged and if just ranged what does the same for melee?

Nope, as the name already implies, gunslinging requires a gun (a pistol, to be precise). I haven't found an equivalent melee talent, though it isn't needed as sorely, as you can already get up to four attacks at a -10 penalty (Lightning Attack & TWF & Ambidextrous).