Things I did not understand or could not find.

1. Point Blank - a. What range is considered point blank ?, b. Would a person in close combat with a pistol be at PB ?

2. Shooting into Melee - a. The Arbites player used a combat shotgun at 3 meters but the creature had extended reach, should he have been considered in close combat ?

This is all I could think of now, I am sure as I remember the session I will remember more.

3m is point blank.

Pistols don't count as Point Blank when used at melee range. Unlike other weapons however, they can still fire.

As others have said, 3m is point blank, and no, firing weapons while locked in melee do not get the point blank bonus.

As also mentioned, only pistols may fire in close combat.

In the example you provided of a creature with reach, there has been no good consensus as far as I can tell, regarding exactly when someone is "locked in melee." Personally, I require an attack to be made before to combatants are considered to be locked in melee. Otherwise, the optimal strategy is to always perform a run action so that you wind up adjacent to the guy with the heavy stubber. Its a very counter intuitive method of "locking up" the guy with the heavy weapon (sure, he should be using suppressing fire and overwatch, but still,). Clearly, such a move might work, but the shooter would still have a last moment to be able to fire before you pull it off.

Technically, the rogue trader rules somewhat side with this, stating that to be locked in melee, an attack must be made (but it is also unclear if the first attack is implicitly locked in melee as well). It would not follow for that to be the case, as it would then be impossible to every make "proper" use of a shotgun's scatter effect.

So for me, if the creature has not made an attack, the shooter would still be able to fire the shotgun (a basic weapon), and receive the point blank bonus (as he is < 3). At this point, I would consider them locked in melee (or at the very least, a creature would quickly respond to this and make it so they are locked in melee).