What should be the role of other person I involve in Startup given my scenario

What shall be the role of the person I am involving in launching my start-up(about to register and launch), As initially I see me and him performing project management part of it(as implementation part we are going to outsource to a local vendor) then few years down the lane we shall start implementation part ourselves by expanding. Now as initially no capital is needed(need no office, can work at my or his place) he need not invest anything now, and for later investment we gonna save 20% of total profit earned in form of cash-reserves each year. Now I have brought these projects to start with due to my business rapport and have chosen him to help me in successful execution of each because he is a close friend, technically efficient or equal of mine, sincere and a person I can trust too.

Now the questions is :

1. I alone cannot handle it completely right from starting and sooner or later I may need another partner who can help me in building a brand for my startup. so Should I involve him as a Co founder & Director with me being the CEO & Fonder, I am okay with this until it conflict with below issues.
2. He shall quit his job and be full time involved with day to day interaction with local vendor or client to assist implementation, monitoring or supervision of progress, risk management, and accounts. and I shall contribute nearly 25% of my full time to it and shall continue my full time software job at some MNC(as profit margins are very low for us in these project, and secondly we both need not put fulltime atleast initially). I may eventually(in a year or half) come fulltime onboard if meanwhile I can find some new projects or if we decide to expand. Any better suggestions ?
3. How shall I decide our stake/shares?, So far I have thought of 60% for me and 40% for him as company stake and profits sharing. But would 50-50 stake and profit sharing can be dangerous for me in case if he wish to part his ways, or if he doesn't perform as expected and I wish to eliminate him and bring in other guy? or can it turn up into some problem for me in future? OR
   as we both are currently working at same career level and kind of similiar pay in different MNC's, so I shall keep stake as 60-40, and share profit 50-50 initially(until profit margin increases in future, and then I can revise it to 60-40),
   How would such a contract work, and does this needs to be done when we register our company or I can make this contract later ? Any better suggestions ?

I shall be very thankful if you can briefly touch upon each points.

Thanks in advance!

If you are doing an LLC make him a Partner or Owner. If you are doing a corp make him a VP. Take a look at corporate structure on google. You can easily gain a feel for what works best with your situation. One word of caution. Title is absolutly the most irrelivant thing on the planet when it comes to owners & senior executives of a startup. You are going to do everything whether you want to or not. Pick something that works and modify it when the time comes.

Only you know your situation and margins completely. When you transition is certainly the million dollar question. If the company strategy is not designed from the get go to make both of you 100% in the company and getting paid for your work then I would suggest getting out while you are ahead. Someone once told me. "Don't Dabble". Either be in business and make that your business, or get out. Otherwise its a hobby that will consume vast resources (time, money, emotional equity)

Lots of different way to look at this. 1) 60/40 is nice because there is a clear leader. Voting will be easier when it comes time. 2)50/50 is great if you are wanting to take ego off the playing field and strive for that truly collaberative feel. You should search the web for what is known as an operating agreement. It will define who/what/when/how/why etc. Its a good idea to have a lawyer review it but theres a lot of cost involved there. Places like RocketLayer / LegalZoom etc may be able to help for less.