1. Unlimited (even beyond expiration date of the HRP). But you need to register at your local police station within 24 hours if you stay anywhere other than a hotel open to non-mainlanders.
2. Yes, you can work in mainland China legally if holding a Work Permit. You may consider working illegally without a Work Permit if your employer cannot get one for you (though it is actually easy).
Originally Posted by star-anise:
This has probably been asked before, but does anyone know if there is any restrictions on Home return permit in terms of:
1. Maximum no. Of days permitted to remain in the mainland! (I heard max. 90 days?)
2. Can home return permit holders work in China at all?