There are no specific rules or laws about what a MD can do or cannot do in a company. The rules and laws of a company are governed by its Memorendum of Association and Articles of Association. The MOA and AOA are registered with ROC at the time of incoporation of the company under The Company's Act,1956. Any amendment in MOA and AOA can be carried out by passing special resolution in AGM/EGM and notifying the ROC about the amendment.
Coming to your questions,
1. An MD can have only those special rights which have been vested onto him in MOA/AOA. No other special rights can be enjoyed by an MD or any Director.
2. No. It is not possible to appoint any Director without the consent of BOD as well as other Members,if any, of the company.
3.The MD of a company has a ficuciary position only. He cannot act as owner or sole proprietor of a company. For transferring/selling/acquiring any/all assets of a company, the consent of majority of BOD/ Members is necessary. The MD/Director/Other member is free only to sell his shares in the company.
Regarding the other Director appointing his wife as third Director in the company through an EGM without serving a Notice to you about EGM and its agenda is unlawful. You can sue the company as well as the other Director for Oppression.