Dispute among directors in a private limited company

Hi Sir/Madam, There are total 4 directors in my private limited company doing business through Govt. Tenders - Myself, My Wife, My friend and his wife having equal share capital. Me and my friend were the only active partners since beginning to running the business. Now for the last 2 years, my friend was actively involve in politics and therefor neglected work. Now he has joined a company as a full time employee from June, though I was aware of it, he has informed me about this only last week. When I started raising questions about the future business of our company, initially he ignored as he was exploring his future in politics ans was not sure what to do. Later on my repeated insisting , we finally came to a mutual agreement on a plane paper with our CA as a the mediator and was also shared on the mail of all three of us. As per this agreement 1. Any one of us was free to do business in the name of the company by doing his own investment using the company's 18 years long credentials. 2. In return the other director was entitled to get equal share in TDS. 3. And he is also entitled to use the credentials earned by the the other director to do business of his own. Based upon that I started exploring business opportunities , and acquired some work by investing my time and money. Meanwhile, my partner also joined some other company working there as a full time employee from the month of June 2014. Now, since he has lost total interest in our old company, he has started creating problems by sending mails to me and threatening me to close the company. I have replied him that since I am interested to run the business and he is interested to close it, better we should sit together and find a solution. But he is willing to go to ROC and then court for better settlement. Here my queries are - 1. Does the agreement on the plane paper along with the sign of the auditor stand legally? 2. Can a director of a Private Ltd co. be a full time employee of another company ? 3. Can the share holders (my friend and his wife holding 50 % of the total share capital) close the company as I and my wife ( holding 50 % of the total share capital) want to run the company, as he has been constantly threatening me to close the company for the last one year. 4. In case he agrees to resign (as he is constantly saying through his mails that he is not interested to run the company) then what can be the possible implications on me. Kindly guide me. Thanks and regards.