Allow me to answer your questions WRT your next door neighbor country.
1)What happens to jobless pilots? Do they ever get a job or seek other career? Some jobless pilots attend Flight Instructor training schools, (additional 30 hours to endorse that rating) and build experience on meager salaries / wages. Sometimes theres no salary at all. Depends. Others stick around, try to opt for Pay 2 Fly programs to get into low cost carriers. Some just wait for the right opportunity (chances of which are quite thing is you don't have "hours" of experience). I personally know some pilots who are pursuing other careers and waiting for a chance to enter airlines. That's how it is. Pilots having experience eventually do get picked up by airlines as far as I have seen.
2)How much time it will take to get behind the wheels of an aircraft after finishing CPL training? That depends entirely on airline requirements. No one can give you a definite answer
3)When should one consider getting ATPL? After you are done with 1500 hours of flight time. ATPL is primarily required for flying heavy category aircraft (A330,A340,B747,B777 etc ) and to command an aircraft. You will be eligible to sit in the ATPL exams after you have 1500 hours. No worries on that. I do not know if India issues a frozen ATPL but here they do not.
4)How much is the salary of an airline pilot? How much time will it take to recover the money spent in training? Depends on the airline, no definite answer again. What I can tell you that flying turboprops pays less than flying jets.
5)What happens if an airline pilot becomes medically unfit after flying for good amount of time? Will he loose his job permanently or may resume his job after getting treatment? What kind of medical problems can cause permanent termination of job? Depends on the medical issue. Serious issues may ground you for life. Some CAA authorities allow the pilot to get his medical fitness and head back to flying. Others (such as some middle eastern carriers) do not give you a second chance. In India I suppose you get a chance to fly again if you get your fitness back. My father lost his job because of a heart condition. So it happens.
I am planning to opt for career in aviation once I finish with my college degree. I don't have any interest in engineering but I think it is always better to be on safe side if I don't become successful as a pilot (although I am sure I will, only thing is I need proper answer to the above questions).
Don't ride two boats at one time. That's my advise to you. If you want to fly, fly properly and enjoy your flying. Your hardwork combined will luck will get you a decent job. If you have an engineering job that pays you well, consider flying as a part time option.