Sole proprietorship’s equivalent for partnership business

I am into freelance web/software development along side my job. I have done fairly enough work like that and am getting quite a few projects. I want to take a stab at setting up my own company for the same. However, i still want to do this as a very basic startup, similar to a sole proprietorship business. The problem is that I work along with a friend of mine and if at all a company is set up for this work, it has to include both of us. What kind of registration should I go for that requires:

1. least legal and paperwork

2. winding up should be easy enough

3 there’s no fixed frequency of the earnings so I should not be liable to pay any taxes if I do not work for a very longer period

4. the taxes that are to be paid, should be only applicable if I have delivered a project and received some payment

Is setting up an office, mandatrory? Or can it be operated from home?

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4. Startup looking for a residential Office – Laws?
5. A business that can be sold :)