Income tax doubts for a webmaster

Aslam (16 Points)

10 May 2007  
Hello everyone.
I am a webmaster earning decent income from my websites for the past one year.

Previously as a govt employee, I used to submit my income tax return as usual along with form 16 with the tax deducted at source.
Now I have earned around Rs. 5 lakhs from my websites using adsense and affiliate programs in the year 2006-7. The payments include cheques in US dollars, bank transfers and cheques in indian rupees from Google and paypal, most of the earnings are advertising revenues from US based companies.
I have a few questions regarding how I should go about with my income tax. I am thoroughly confused as  have no prior experience.

1) Should I pay tax for the entire income? Are there any exemptions on foreign income?

2) Can I just show the entire income as "Website Income" in the return? Should I need to show any proof and if yes, what?

3) Can I claim tax exemption for my expenses for running the website including hosting fees and money spent for purchasing or upgrading computers? Should I need to show any proof for this?

4) When should I pay the tax? My friend told me that today, March 15, is the last date for paying income tax. Can I pay the same later and if so, is there any fine?

Answers would be greatly appreciated