First property in GGN: Kya kya bhool raha hoon?

DLF Phase 3 area mein property dekh raha hoon, but kuch samajh nahi aa raha. Laburnum Developers ka ek under-construction project pasand aaya hai. Delivery risk kitna hota hai aise projects mein? Meri biggest worry hai hidden costs. Property price ke upar kitna extra budget rakhna padta hai for stamp duty, registration, interiors, aur misc expenses? First-time buyer hoon, kya cheezein koi nahi batata jo later pata chalti hain? Any advice will be helpful.