Career in Islamic Banking

I would like to know the following (i) A person works in a Management Consultancy firm (like a Sharik Ammal but might not be the same) where two people are partners. One partner is an ex-conventional banker who has worked as an investment banker (interest). Is this a valid partnership (ii) A person who is an employee and receives salary from such a partnership fund pool is it halal. (iii) The firm offers its services to various organizations including tv channels, conventional banks, software houses that produce banking software, advertising companies etc. Are these services permissible like recruiting people for these organizations, developing organizational structure, preparing their duty list, facilitating their management etc. (iv) Why are current accounts in conventional banks permissible since they are also loans which are used by the conventional banks in interest based activities (v) Islamic Banks are not able to fully practice Islamic banking because of government laws and restrictions (tax structure, insurance requirements) thus is it permissible to opt for these banks for career motives (vi) Many conventional banks have opened sub divisions of Islamic banking yet their mainstay of business still is conventional banking. Are we allowed to work in these Islamic banking divisions I don’t know if there is intermingling of funds. Can you give some detailed explanations?