Not tough but neither easy. See 10% people get a cgpa above 8 and you need to attend all classes and work a bit regularly. But due to zero attendance rule and a lot of activities students forget their initial enthusiasm and then give up. So you need to be focussed.
Goa campus offers electives and courses in finance and management but i am not very sure of the minor thing i will find out and let you know.
I like youe dedication and its mot unachievable. Many students do it. So you can! Dont worry. But yes dont depend on a branch change and come. Things change but many people do it with their efforts.
First year syllabus is same for all branches. Its mostly a revision of your jee stuff in first sem. Courses would be like chemistry, physics, maths, probability and so on. Chemistry will be organic and physical mostly and just 1 or 2 chapters of inorganic. Physics is going to be mechanics. You can get along your PHY and chem notes of jee for reference. Dont worry its manageable.