M.Sc

Yes, you can take surely as age restrictions in the master's degree is a very rare case in some colleges only.
All the best.

http://www.gdgoenkauniversity.com/schoolofmedallied/academics/#masters
Above is the link for available courses available in G.D. Goenka University.

You have got a very good percentage. It is a hard choice to make as which subject to choose for M.Sc. Since there are many options available. You should first recognize your the strongest subject and in which you are interested more, and pursue the same.

The college has got a good rating for MSc in botany.

For the first question, you have to practice still life in pencil. Just pick any random objects of different materials, place them and start making them on paper. Make sure you shade background and foreground as well. The second question will be based on your specialisation, for eg: applied art candidates will be expected to make a composition on given topics in mediums such as water color, poster, pencil color, oil pastels, etc. The final question will comprise of theory questions related to art. It's not too difficult, all the best.

Can you please tell me the college you wish to take admission in so that I can guide you better and a bit specifically?

Why not, sure you can pursue but mathematics is compulsory. There is basic mathematics in CS that's don't worry about mathematics. Let it happen.