You ask questions - You answer questions - you publish trips - everything earns you credits.
The only way you can redeem them: By buying a trip package from tripoto.
1 Credit = 4 INR
Can you get a trip free if you have credits more than the value of the package?
No. Every package has a set number of credits which can be used. Some may allow 20% credit usage or some may allow 80% of the entire package price.
The only way to find out is by trying to buy a trip.
Haven't visited but remember this, the only 3 things that are responsible for your costs are:
1. Travel
2. Accommodation
3. Food.
Use public transports, eat local food, use cheaper accommodation and you may save thousands. Use platforms like airbnb, couchsurfing to find cheap or free stays.