For list of good colleges take a look at the following website: https://bschool.careers360.com/colleges/ranking/2016/top-mba-colleges-in-India-accepting-cmat-score

For the preparation part firstly try to get a hold of all the topics in quant. Then start giving mock tests. Give as many as you can as it will help you get better. You will be able to manage your time better and get to know where you need to work upon. Subscribe to online websites like testfunda, oliveboard etc where a lot of people give tests as it will help you get an idea of where you stand. 

You will have to analyse each test you give and know where you need to work upon. Practice makes one perfect and this is absolutely true for competitive exams in India. So the idea is to give as many mock test as you can.

Yes, you can definitely get good colleges through CMAT exam also. Here are some of the top colleges which gives admission through CMAT exam.

• Great Lakes Institute of Management, Chennai
• Prin. LN Welingkar Institute of Management Development and Research, Mumbai
• Goa Institute of Management, Goa
• Institute of Public Enterprise, Hyderabad
• Xavier Institute of Management and Entrepreneurship, Bangalore
• Birla Institute of Technology, Mesra
• Alliance School of Business, Bangalore
• Balaji Institute of Modern Management, Pune
• Shri Dharmasthala Manjunatheshwara Institute for Management Development, Mysore
• Myra School of Business, Mysore
• Jaipuria Institute of Management, Lucknow
• Thiagarajar School of Management, Thirupparankundram
• Institute of Management Technology, Hyderabad

For more information you can check out this link:

https://bschool.careers360.com/colleges/ranking/2017/top-mba-colleges-in-India-accepting-cmat-score