Tax filing for non-resident if income less than 1.8 lacs

Is 2011-2012 Tax filing required for non-residents if income from India is less than 1.8 lacs/year?

I am a male and my income from India is interest from savings bank accounts, fixed deposits, dividends from
equity mutual funds. Income from all of these is 1.5 lacs for 2011-2012 tax year(April 1, 2011 to Mar 31, 2012).

1. Since I am working overseas, I do have bank accounts in that country. Are these(bank accounts) considered foreign assets due to which I have to mandatorily file income tax?

2. Does the mandatory filing rule for folks with income over 10 lacs/year apply to non-residents like me?

3. I realize if I am getting any refunds like tax deducted from non-resident ordinary accounts or if I wish
to avail indexation benefits, a tax return is required for me to get those, but it is not
necessary as per the Income tax law to file tax returns since my income from India is less than 1.8lacs for 2011-2012 year. Is my understanding correct?

4. Any other factors I need to be aware of?

Thanks