Diploma

You may refer to the link below:
https://goo.gl/j2sTeq

Percentage for direct second year or lateral entry into the B.Tech course requires minimum percentage of 60% in your diploma in Engineering and secondly donation is the amount that some colleges take from the students but not all colleges or universities donation amount really where is but college fees or universities I can give you an idea that it really where is between 3 to 4 or 5 to 6 lacs, depending on the status of the university. I have also taken the lateral entry so I know the fact.

Dear,
Diploma won't give you rich course structure and better opportunities. According to me you should plan for Master's degree in related field or think of CA or CS or MBA finance for better knowledge and expertise.

Finance is a very broad field. A person may play various roles. Financial Analyst, Financial advisor, Budget planner so on are various roles a person may get opportunity into. I hope this would suffice. God bless you.

Yes, polytechnic diploma is equivalent to intermediate that is 12th. You can get admission in B.Sc degree course in lateral entry mode after clearing polytechnic diploma course.
B.Sc Lateral Entry:
Duration: 2 years (Semester System)
Eligibility criteria (Qualifying Exam):
You have to clear 3 year's Diploma course after clearing 10th with minimum 50% aggregate marks in diploma course.