The market for CAD services is very competitive. So identify your strengths. Some things you need to get clear about.

What your long term goals?
Whose will be prospective customers?
Why clients should come to you?
What's special about your service?

Everything you can highlight via project profile. You need to take on projects that require detailed design knowledge in addition to drafting skills.
Best of luck.

You can use both. Professional designers should constantly study on the desktop. But if you are interested to use a laptop then the best laptops are HP Envy 13-ab016nr, Dell Inspiron 5567, MSI GV62 8RD-200