Pros and cons of legal agreement of tenancy

I have come to bangalore for treatment purpose and staying in kormangala for last 4 months.I stay in a rented 1bhk flat the building of which is taken on lease for flat rental business.The business owner dint make any legal agreement with me.Now the business owner has changed and the new guy wanted to increase rent by Rs 3k/month from the 3rd month onwards.As i told him it snt possible for me and I might have to look for another flat,he continued to take rent on previous agreed rate.Now, today he sent a guy to remove AC from my flat without any prior talks that too for a month cycle for which I have already paid advance rent.On calling him he simply said that the rent I am paying is for non-AC flats and for AC I will have to pay higher. I want to go for an agreement incase I agree for the increase so that the rent doesnt increase further in the coming 1yr or so.A fellow tenant who has been staying in banglore for yrs has advised me against going into an agreement. 1)I request for your advise as to what difficulties I may face if I do an agreement legally 2)What is the limit of security deposit that I might have to pay and will I get the full amount back? 3)What will be my rights(protection from eviction/harrasment/rent increase/etc) in that situation? 4)Incase the agreement is of 1yr and my treatment gets over before that then do i need to pay extra rent (like 1month's rent more than my stay) for vacating early? 5)What will be the status of the agreement incase the business owner changes again? 6)Is the building owner's signature mandatory?(He stays in Qatar) I am completely unaware of the tenant laws in bangalore so I would be grateful for your advice.Besides legal advice I would appreciate if you could give me practical advice based on ground reality of the city.I dont want to leave the flat as a 1st choice as its well suited to all my requirements and medical limitations. It seems the business owner has taken up the business from the rightfull owner of the building though I am not sure if their agreement is in papers or verbal. The new guy has already evicted a tenant after harassing him by disconnecting electricity at nights etc due to some personal conflicts,as i heard.He is v aggressive in his business management and is renting out rooms on daily basis(like hotels) since most of the flats are empty (people visiting for monthly rent dint agree to his increased rates). Thank you for your valuable time and advice.