Any good summary of D1's lore and story?
Unless you want to read all the grimoire cards, which you can find just about anywhere online, there really isn't much of a story in-game. The in-game story is something like...
You're resurrected and need to fight off Fallen. You kill them, get a ship, wake up the Warmind and are sent to the moon to fight those dastardly wizards (Hive). On the moon you find out about some guy named Crota, who you basically kill in the first expansion, and meet up with a girl who doesn't have time to explain what she doesn't have time to explain. Eventually you head to Venus, where she is still busy, and you find out about these organic machines (Vex) that can travel through time. There you get an eye to give to the Awoken Queen who tells you to take it to Mars to open the gate and stop the Vex. When you go there you piss off the Cabal (guys D2 seems to be about) and then you go through a gate and kill a black blob.
After the story you go into a vault and kill a guy who does something related to Time. As mentioned above, you kill Crota and then Skolas escapes from the prison. He thinks he is the chosen one, leading to the Fallen under the Awoken to rebel. He gets captured and then you kill him in the Prison to prove your power.
Taken King starts with Crota's dad coming to kill you, but after sneaking on his ship and doing a series of things to get the power to enter a special room, you fight and defeat Oryx. You then go on another quest to stop him and ultimately defeat him and his heart is turned into a weapon. Sometime later one of his followers starts to cause trouble, but you quickly dispatch him.
Rise of Iron involves non machines son! You go to where it started and stop them. Shortly after you're sent to kill their leader infected by SIVA (Aksis) and that's basically where the story ends.
There are some minor things that happen, like the Cabal try to take out Oryx and killing the Bond Brothers sets up what seems to be happening in Destiny 2, but even this version of the story has things not explicitly stated in-game. A lot of the events just happen or are given some context. Like, the Bond Brother strike boils down to being to like three lines. They were told to do this, they don't retreat and they won't be happy about losing all their ranking officers in this area.
How is Destiny's PvP multiplayer played compared to, say, Call of Duty?
Given what little we know about Destiny 2, it's hard to say how things will change. Previously it was woefully imbalanced and the whole point in leaving our gear behind is suspected to be over balancing. Obviously if a new system is in place, it will play differently.
Do Bungie devs hang around here often?
Sometimes people from Bungie post something, but I can't say I see it terribly often. Usually when people are mad about something or they screwed something up.