1. Would I be lost if I didn't play 1? = No 2. Any DLC? = Yes 3. Is it worth getting the DLC? = Yes 4. Tips? = BUY IT! 5. Thanks = Your welcome.
All kidding aside this is a great game and I would recommend it to any FPS fan. I would describe it as a FPS loot based game with RPG elements and a strong CO-OP presence. I wouldn't worry about the DLC until you really feel like your needing something new. The vanilla version alone should keep you busy for months. Even then you won't be any where near finished, (Legendary loot,challenges,etc), or atleast I'm not and I've played since launch. That includes 4 level 50characters. I don't think you'll be disappointed. Give it a shot!
"Now I want you to remember that no bastard ever won a war by dying for his country. He won it by making the other poor bastard die for his."-G. S. P.