• Maintenance suit under CrPC 125

My father has filed a maintenance suite against me under 125 CRPC in family court and has demanded 20000 per month as maintenance and 22000 as litigation expenses. I put the following facts for your review.
My family includes my wife and a 4 year old son. My wife is suffering from rheumatoid-arthritis and she requires constant medication and regular check-ups that would continue throughout her life. Her medicines and injections alone take around 3-4 thousand a month besides other household expenses. She might have to go under knee transplant in upcoming year that would again require a good amount of money. Apart from this, monthly travel expenses (to-from) office is around 4 thousand.
I live in my father's house at first floor with my own family since Jan-2008 when they (my mother & father) had separated me from themselves and asked me to live at your own. Since then I've been living upstairs.
While living upstairs, I did not give my parents any fixed monthly amount on regular basis. However, I kept on helping them as and when required like - purchasing medicines sometimes, bearing whole expenses of maintenance and fixations of house including water arrangement etc. Paying 50% of monthly electricity bill irrespective of my low usage in a given month.
I have also spent money during the hospitalization of my father (in 2012) and my mother (in 2014) around 70000/-.
I had asked them to go for treatment in a relatively cheaper of govt. hospitals like AIIMS as we cannot afford that much of medical expenses. However, my brother denied.
My father has retired from a NGO and he does not have any regular source of income. Though, he gets family pension from EPFO and Sr. Citizen Pension from Delhi Govt. That sums close to 2500-3000 in a month.
I believe my father had got a good amount at the time of his retirement in Dec-2007 that included gratuity and PF. I suspect they had given major part of this money to my brother and sister for their settlement and still have a considerable amount in their bank account (including savings & FDs).
We are three siblings I am the eldest one. Besides me, I have one younger sister who is married and settled in her marital life in Pune and a younger brother who runs his own business of gym (fitness centre) and giving personal trainings to his clients. Both have good relations with my parents. 
In comparison to me, my younger brother is financially sound and lives a luxurious life. He own a car and motorcycle and lives separately in a rented flat in close vicinity due to his personal reasons (living relationship). He also went on foreign trips in South Africa and Singapore in the years of 2010 & 2011 respectively. I believe his travel expenses were either partly or fully funded by my father.

For a long time, my parents want me to vacate their house and live somewhere else on rent. However, I am not ready to vacate as I have spent a good amount in construction of this house including ground floor. Since, house papers are in the name of my mother & father; they always keep on asking me to live this house without given any share to me or at-least what I have spent on constructions.
Considering my income and monthly expenses, I am ready to give them a fixed monthly amount of Rs. 1500-2000/- that is additional to month electricity bill that pay 50%. However, they are not ready to accept it. 
They know law is in their favor and want me to vacate the house and claim the maintenance under 125 CRPC too. 
For, me it would not be possible at all to give them any maintenance after vacating the house as I'd have to pay for house rent that could be anywhere between 6-10 thousand a month.
They are also (with my younger brother and sister), threatening me to entrap me under any false case. In January 2014, they have already submitted a precautionary complaint in local police station wherein they've alleged that they have life threat from me and my wife.
In case, I do not vacate house, they are threatening me to file a case against to vacate the house.
I feel helpless. Please help with the right guidance and let me know the followings:
1.	Considering my private job and income (25000 per month) per ITR as well as my living expenses, maximum how much amount court can order me to pay him as monthly maintenance?
2.	I do private job with high certainty of losing it in upcoming months due to some internal business decision of company. What if I lose my job and remain unemployed? How court would consider this?
3.	Is there anyway I can avoid vacating the house? With or without maintenance?
4.	Generally how long does it take for the court to reach the judgment (minimum) in such cases?
5.	If my parents have three children, so the maintenance should be divided among all the three children including the married daughter (as legally she can claim the share in father's property) and not only me?