Quote: "will I be able to create an open world First Person RPG with this engine?"
Absolutely.
Quote: "Can I make NPC's have dialog options and to get quests from them?"
It's not currently an engine feature, but it could be scripted pretty easily enough at this time. I believe it will probably be an engine feature at some pint.
Quote: "Is it just me or is it like this because the engine still needs work?"
LOL, it still needs work! The last beta was actually quite a bit faster! It seems some betas can be one step forward and two steps back! It's coming along, though. Keep in mind TGC is a very small company/development team.
Quote: "It seems to take a long time to kill the bad guys. I have to pump tons of bullets into them."
Yeah, the guns aren't that accurate! Apparently you can tweak the accuracy, or was that due for the next beta? I don't remember, I kinda lost track of that one and I've never tried it! Try shooting a few rounds at the same point like the ground, water, or whatever, and you'll see what I mean. Also, the bad guys have adjustable health levels, so you could go that route, too!
Anyway, welcome to the forums!
Quote: "Are there scripted doors that open and in the buildings? Except for the fence and a rock door the demo didn't have any scripted doors."
Oops! Missed one! They won't be working on interiors until at least the conkit is finished. Performance issues need to be addressed first, I think. Also, outdoor lighting has it's own flaws in the current beta. There are no accessible buildings in their entirety, you kinda have to assemble them from parts available in the store, or make them yourself (horror pack, I think, works). it's just that interior lighting is not very good. There are people around here that are quite skilled in the martial arts of shaders, scripting, and modeling, and they could certainly pull it off! Take a look at some of Rolfy's work in particular!
Quote: "Will there be a day/night cycle?"
Missed another! LOL! Sorry, it's Friday and tomorrow is my first day off in a couple weeks and I'm enjoying some libations! We got flooded, big time! Anyway, day/night cycle has already been implemented (last beta, I think). I just don't know if we have any real control over it.
MAME Cab PC: i7 4770@3.4Ghz (passmark 9945), 12GB RAM, Win 8.1/64, GeForce GTX645 (passmark 1898); Shiny new laptop: i7 4800MQ@2.7Ghz (passmark 8586), 16GB RAM, Win 8.1/64, GeForce GTX870M (passmark 3598); Old laptop: i5@2.3Ghz, 8GB RAM, Win 7/64, Intel 3000 graphics