Diploma

You can opt for lateral entry in Civil Engineering under Engineering colleges. This scheme gives you direct entry into 2nd year.

We are having extraordinary future in cosmetic Science Bachelors degree try to get one. It is an extraordinary field and you will have nice future.

Degree is better option if you have completed your graduation in Fashion Designing.

Based on your local entrance exam, you're going to get a seat in the concerned Bachelors college. Not based on your percentage but based on your test, they are going to allot a seat for you.

Yes,
You can go for BCA after completing your diploma in CS. You should go with that because it seems a very good career opportunities in it.

Yes, you can take up a Diploma in interior designing after 10th. Alternately you can do 10+2 and then do a Bachelors in interior designing. The latter is a better option in fact in my opinion.

Since you have a Diploma, get few years of work experience to get good hands on exposure or even an active internship. Post that, if you think you want to continue with Bachelors for higher career prospects. You will also know what exact specialisation course to highlight and study at Bachelor level.

You have diverse Diploma options. Example, Diploma in arts, animation, beauty culture and hair dressing, cosmetology, hotel, hospitality and travel and tourism management, various option of engineering, fashion designing, interior designing or other designing like textiles, apparel, jewelry.