Pls clear some of my doubts
1. will amber update add up any functionality to it?
Yes. FM radio and 'fix' for 'others' storage bug.
2. which games are supported both free and paid?
I am not sure what you meant. A lot of games from android are missing on WP.
3. What are the payment mode to purchase game and app?
Based on credit cards, AFAIK.
4. Is there wifi hotspot ?
Yes, but not via USB tethering.
5. Do we get gps and all sensors?
Yes, all except compass. This also means that L520 doesnt support Nokia city lens app.
6. 512 mb ram will suffice or not unlike android which lags after few days and moderate apps.
Yes. 512MB is sufficient for any lag free usage. But some games and apps are out of reach because of this.
7. Lack of file mgr in wp, will this hamper in any way?
Yes, this can be a problem, especially for people who are used to the android ways.
8. Is resale value better? May sell it off in 6 mnths if do not like wp ecosystem.
No idea, but Nokias generally tend to have better resale value.
9. Pls shed some light on nokia music.
Lets you download music legally for a period of 3 months and listen to it.
Thanks in advance