1 ) If you are letting out the flat directly to the tenant, then the whole amount of Rs. 55,000/- p.m. will have to be added as your rental income. The TDS will be given credit against your tax liability and you may need to pay more or claim refund depending upon your actual tax liability. For example, if the TDS is say, Rs 30,000/- and your tax liability is Rs. 25,000/-, you will get a refund of Rs 5,000/- after filing your Income Tax return. On the other hand if your tax liability is Rs 35,000/-, you need to pay the balance amount of Rs. 5,000/-.
2) The property management fee will not be allowed as a deduction in your rental income. You will get a standard deduction of 30% u/s 24 of the Income Tax Act. You can claim in addition, payments towards property tax and interest on your housing loan.
3) You may plan the transaction in a different manner, if possible. You can let out your flat to the Property Management Company, which can sub- let it to the actual tenant. In that case, you will be offering to tax only the rent you've received from the property management company.
4) If you are letting out as a business person, then you can claim input credit for the GST paid by you.