My answers to your questions are:-
(a) Yes, you are eligible to work as Lecturer in Engineering Colleges. However, kindly note that most of the Engineering Colleges prefer candidates with specialization in Industrial Chemistry or in similar applied Chemistry subject(s).
(b) Qualifying National Eligibility Test (NET) would help you to apply for the post of Lecturer in Government Engineering Colleges as well as other Government Colleges. As far as private Engineering Colleges are concerned, this provision (qualifying the NET) is not compulsory, but desirable.
(c) Is it possible for a fresher to have teaching experience? There must be some entry point for every experienced Lecturer. Teaching experience is again not compulsory, but desirable.
(d) In Government Engineering Colleges, there is a fixed pay scale. At the entry point, a Lecturer gets around Rs. 60,000/- p.m. in smaller cities and Rs. 75,000/- p.m. in metro cities (approximately). However, in private Engineering Colleges, there is no fixed scale. A freshly recruited Lecturer can expect a consolidated pay of Rs. 30,000/- p.m.
Come as you are!