Diploma

Yes, you can do Bachelor's degree from USA, UK, Australia. For that you need an exam i.e IELTS.

Hi,
You can get some help from the following link
https://www.shiksha.com/engineering/colleges/distance-correspondence-diploma-mechanical-engineering-courses-india
Thank you.

Hi,
Pondicherry University conducts its own entrance exam which is online mode and whosoever gets the qualifying will be eligible for the next level.
Thank you.

All institute have their own fee criteria if the institution is good then it definitely charges a high amount, but if the institute is not so good or bad then its fee may be less around INR. 50 to INR. 80 thousand. If you apply in a top 10 institute then their fee is around INR. 1 to INR. 2 lakhs.

Hello,
As per my knowledge, the total fee is around 100000/-.

You have not mentioned about the specific college. However, IIFD offers Diploma in interior design course. The course duration is varied according to qualifications, means if you are graduate than you can complete the course in one year. While for 10+2 the course duration is two years. For admission you may fill and submit application form online by using http://iifd.in/online-application/

Hi,
Distance Diploma is a correspondence teaching distance education and you can apply in these distance Diploma colleges:
1-Venketshawra Open University
2-suresh Gyan Vihar University
3-Indian Management Academy
4-Kosmo Education

You can get the complete list of engineering colleges here:
https://www.shiksha.com/b-tech/colleges/b-tech-colleges-india

GICED has the following interior design courses as under:
1. Post graduate Diploma in Interior design (PGDID)
a) Course duration : Two years
b) Course fee : Rs 82020
c) Eligibility: Degree from any stream but with flair for good sketching/drawing.
d) Admission : Written test+Interview
2. Bachelor in Interior Design (BID)
e) Course duration : Three years
f) Course fee : Rs 240000
g) Eligibility : The candidate shall be HSC with 50% marks from any stream.
h) Admission : Written test+Interview