Minimum 2 partners are required. There is no limit for maximum number of Partners. Minors cannot be partner in a firm.
No limit. Can be started with even Rs 10,000.
With Income Tax Department:
Partnership firm and Partners have to file Income Tax Return annually
Advance tax needs to be paid periodically
Tax audit has to be got done by CA and audit report needs to be collected in case annual turnover is more than Rs 1
crore in case of trading business or Rs 50 lakh in case of professional business.
Others:
GST returns to be filed online monthly
TDS returns of Salary paid and vendor payment is to be filed quarterly, if applicable
Other need based compliances
Every partnership firm has to prepare balance sheet and profit and loss account and file Income tax return, even if there is no transaction or there is loss.
