Job & Visa Requirements

1) What is the pay that i can expect
Expat pays differ from our domestic market rates drastically.

2) Cost of Living for a family of 4 with 1 kid in school

With rent, transport and kid in international school and living a luxurious life with gym facilities and dining out etc a minimum of Rs. 500,000 per month

If you want to live a little outside Colombo and you cook at home and don't use A/C much etc you can cut it down to Rs. 200,000 per month roughly

3) If I get the job and the company sponsors my visa, will i be able to move to another company after a couple of years. For that , do i have to travel out of Srilanka for the new visa.

Visas are given for Residence based on employment directly to the company and not to the individual. So you will have to obtain a new visa. You may not have to travel to change a visa over, but depends on the circumstances of the new appointment.

4) How safe is Colombo and also whats the rent that i can expect for a 2bhk apartment.

Colombo is very safe just like anywhere else you do have to do the sensible things, like lock your doors, etc.
A 2 bedroomed apartment can vary depending on the geographical location. Have you researched that. You can get a 2 bedroomed apartment from Rs. 50,000 upto Rs. 350,000 per month.