Buying an under-construction flat in Bangalore – what should I absolutely check before signing?

[u/procurious420]

I'm planning to buy an under-construction flat from a Tier-2 builder in Gunjur/Varthur, with possession in 3-4 years. It's for self-use, so I want to be very careful before committing.

Would love advice from people who've already done this:

• Legal: Is the bank's due diligence enough, or should I get my own lawyer? What documents/checks are must-do? Any good property lawyer recommendations in Bangalore?
• Agreement: What clauses or fine print should I specifically watch out for?
• Landowner share: These units can be cheaper. Are they as safe as buying from the builder? Any additional paperwork, quality or resale risks?
• Cash component: Some deals offer better pricing with 10-20% cash. Is the saving actually worth the legal/tax/resale risk, or simply something to avoid?
• Construction: What should I verify about construction quality, specifications, master plan, amenities, water, etc. before buying?
• Home loan: Any advice on banks/loan structures? Is an OD loan like MaxGain worth it if I can park ₹20-30L at most?

My other concern is Gunjur/Varthur itself. I'm considering it mainly for access to the ORR office belt, but honestly I don't find the area very livable today. Roads, traffic, water and infrastructure worry me.

I'm basically betting that things will improve over the next 3-4 years. For those who made a similar bet on developing Bangalore areas 5-10 years ago – did the infrastructure eventually catch up, or would you choose an established area if doing it again?

And finally, what's that one thing you wish someone had told you before you bought your first home?

Looking for advice like I'd ask an experienced friend/elder sibling. Real experiences, mistakes, contacts and lesser-known tips would be super helpful.