hello aspirant, 

yes you can take drop and study for jee main. but think you would have 2 years gap between 12 and starting of btech. and some companies doesnot allow 2 years gap between academic gap. 

and now you are studying in btech and you need to go back to your 12 syllabus and have to study accordingly. see to get a good job from a below average college would be difficult, but there is many resources where you can get good jobs like amcat, elitmas, co cubes exam. first of all make a strong technical knowledge, then finding job will be easier for you.