It seems that your termination is illegal and bad in law. Even if someone is terminated for non-performance, proper warning, show cause is to be given before proceeding with domestic enquiry and finally awarding a harsh punishment like termination. In your case non is followed.
The total amount of benefit post service depends on the tenure of service (so details is required to give a fair idea).
The company cannot deduct the cost of repair of laptop from your salary. First, they need to prove that the damage was due to your faulty. Secondly, the amount (Rs5000) was infact the amount that was spend on the repair of damage of the laptop cause by you. Even if all these factors go against you, your employer cannot deduct/ adjust from your salary or dues. Only option left to them is to recover the said amount from you through money suit.
For more information, check my blog www.labourlawhub.com
It is true that terminating for non performance without giving opportunities for improvement is illegal. But the same without giving the reasons will be legal when it is during the probation period. Therefore, before we come to a conclusion we should also know whether the employee was on probation or not. Moreover, performance is a relative term and would vary with changes in set goals/ KRAs for the year. Due to this good performer in 2014 may be rated average in 2015 when he is given a revised KRA for 2015. An employee promoted in 2014 may be rated bad in the next year because he may not be able to show case the best in 2015. Therefore, it is always difficult to prove before an employer that "I was great".
I personally feel that going legal on such matters would not give any result. Just think that an organisation which insists for mail communication for leaving workplace to washroom is not worth working and therefore, please do not continue there. Leave it right now and forget about the notice and amounts charged by way of penalty etc. You can also advise your friends not to join the company. If you fight you should win and in order to win, you should have proofs and time to spare. The second thing is very important because you may not get leave from another company where you join to appear for hearing etc and don't ever think that the matter will be closed in five years from now.