Gap between attacks?

Both, if with and with out skills. The attack speed is a bit slower when using skills in a combo, so I'm guessing theirs a gap between each attack? Auto-attacking gives you a chance of double striking, which gives you more DPS, the use of attack skills, however, doesn't have that chance. You attack once with Lead and Offhand Attacks, and twice with Dual Attacks.

Daggers have the same attack speed as swords and axes, but on average, they attack more, because of the double strikes.

With critical agility would it be seen as a continues attack since the attacks are coming at a much faster speed? Critical Agility is a form of IAS (Increased Attack Speed). The skill makes you attack 33% faster (so you'll attack 50% more than usual), immensely increasing your DPS (Damage Per Second), yes.

You should still be able to notice, though, that sometimes you only hit once, sometimes hit twice. You can increase the odds of hitting twice by using skills like Locust's Fury, or putting more points in Dagger Mastery.

There is no gap. If you have chosen to attack and are not moving and not using a non-attack skill, you are CONSTANTLY in the state of attacking. Thats the answer I was looking for, thanks lol.