I intend to save maximum income tax from my salary. How is it possible.?

I am 49 year old male working in Central Government of India in one of the A1 class city. MY salary details for the year 2010-11 are as follow.(figures represent total earnings for the year)
basic pay Rs 219060
Grade pay Rs 57600
HRA RS46290
DA Rs 115401
TA Rs 12800
DA ON TA 5440
TOTAL Rs 456591

I was saving an amount of Rs 2000 towards GPF subscription from 3/20010 to 10/2010 and from 11/10 I have to increase it according to my tax requirements.

I am paying interest for the purpose of higher studies of my son in Canada who is studying an advance diploma in electronics which is of post secondary level as per canadian standard but admission is given in this course only to those who have completed 15 years of education in India.

I am having an own house in the city which will be used by my daughter and her in laws and for this purpose I will not be charging rent.

I am staying in a rented accumulation for which I am paying rent of rs 7000/- pm.

My questions are.
What is the best way to save income tax and to what maximum extent I can save tax.

Whether I can claim HRA exemption in presence of my own house which is given to my daughter without rent and that I am residing in a own house.

My mother is a family pensioner who is drawing a Gross pension of about Rs 4700/-. Whether any amount invested for her treatment is eligible for deduction from taxable income. Is she dependent upon me and for what purposes she is dependent upon me.

What are the other ways for saving income tax from my salary.

Apart from saving in GPF what are the other ways to save to get deduction other than Rs one lakh which is elegeble under section 80C. (eg any ELSS scheme). How to select good scheme which will be useful for my son who has completed his engineering and who is in the age of 24 years.