10 years of renting, finally pulling the trigger

Whitefield, my wife and I are seriously looking here for a 3BHK, kids ke school ke paas. Prestige Keya Life By The Lake is one option, but legal checks pe thoda confused hoon. Builder ka track record to acha hai, but RERA registration details kaise cross-verify karein? Matlab, website pe project dikhta hai, but koi hidden issues ya red flags bhi ho sakte hain kya? OC delay ka kitna bada issue hota hai Bengaluru mein? Sunna hai builders possession de dete hain bina OC ke bhi, but is that actually safe? Later koi problem toh nahi aati property registration ya loans mein? Title verification ke liye kya special documents dekhne hote hain? Any advice on this, especially for Prestige projects?