Mainly the fact that you don't have to apply for a job, the company/startup will get in touch with you if you meet their expectations.
Yes it is free for developers.
Yes you can set your expected hourly rate.
We can assist you to get you setup based on the payment method you'd like to get paid with.
Yes, in addition, you can choose to be open for the companies/startups you're only interested in.
You can promote your profile but it will be quite expensive as we think your work describes your skills.