What is a Passport Seva Kendra (PSK)/ Post Office Passport Seva Kendra (POPSK)?
Passport Seva Kendras and Post Office Passport Seva Kendras are extended arms of Passport Offices and render front-end services related to passport issuance. These Kendras cover functionalities from token issuance to granting of application for passport issue/re-issue and other services.

What is a Passport Office (PO)?
Passport Offices (PO) are vested with the authority to issue passports, besides revocation and impounding and exercise control over the PSK(s) under them. They handle all back-end functions required for processing all passport applications. The POs are responsible for (i) printing (ii) lamination (iii) dispatch of Passports,(iv) liaison with MEA Hqs, state /UT admn and police, (v) PVR review, (vi) besides attending to (i) establishment matters, (ii) legal cases, (iii) RTI cases and (iv) financial matters.

Can I apply online for re-issue of passport?
Where to Apply for Passport FAQ | Passport-Sahayata
Yes

Can I apply for Police Clearance Certificate application online?
Yes