Can the EPO complete forms on your behalf (e.g. vendor registration)?

No, as an international organisation, the EPO cannot complete national administrative forms.

Vendor set-up information:

• Legal entity: European Patent Organisation
• Address: Bob-van-Benthem-Platz 1, 80469 Munich, Germany
• VAT: Not applicable. The European Patent Organisation is an international, intergovernmental organisation which currently has 39 member states and enjoys certain privileges and immunities conferred on it by law (European Patent Convention and the Protocol on Privileges and Immunities). Article 4(1) of the Protocol exempts it from all direct taxes on its official activities, which means for example that it does not need a VAT registration number for goods and services provided to third parties as part of its patent information work and other services. 
• Bank details:
  Bank: Commerzbank AG, Landsberger Str. 344, 80687 München
  Account number: 3 338 800 00 (BLZ 700 800 00)
  IBAN: DE20 7008 0000 0333 8800 00, SWIFT/BIC: DRESDEFF700
  If DRESDEFF700 is not recognised, use COBADEFFXXX.
• See also our Transparency portal