The DMCA provides the requirements, found in 17 U.S.C. § 512:
(2) Designated agent.—The limitations on liability established in this subsection apply to a service provider only if the service provider has designated an agent to receive notifications of claimed infringement described in paragraph (3), by making available through its service, including on its website in a location accessible to the public, and by providing to the Copyright Office, substantially the following information:
(A) the name, address, phone number, and electronic mail address of the agent.
(B) other contact information which the Register of Copyrights may deem appropriate.
Stack Exchange provides an example in the terms on each site:
15. Copyright Policy
Stack Exchange has adopted the following policy toward copyright infringement with respect to the Network in accordance with the Digital Millennium Copyright Act. The address of Stack Exchange's Designated Agent for copyright takedown notices (“Designated Agent”) is listed below.
Reporting Copyright Infringements
If You believe that content residing or accessible on the Network infringes a copyright, please send a notice of copyright infringement containing the following information to the Designated Agent at the address below (all received notices will be posted in full to Lumen):
- Identification of the work or material being infringed.
- Identification of the material that is claimed to be infringing, including its location, with sufficient detail so that Stack Exchange is capable of finding and verifying its existence.
- Contact information about the notifying party (the Notifying Party), including name, address, telephone number and e-mail address.
- A statement that the Notifying Party has a good faith belief that the material is not authorized by the copyright owner, its agent or law.
- A statement made under penalty of perjury that the information provided in the notice is accurate and that the Notifying Party is authorized to make the complaint on behalf of the copyright owner.
- The Notifying Party's physical or electronic signature.
Attn: Copyright Agent
Stack Exchange Inc.
110 William St, 28th Floor
New York, NY 10038
Tel: +1 (212) 232-8280
Fax: +1 (212) 785-4578
So yes, you need a physical address. As for whether you should create a form, that is a decision for you to make; creating a form would likely place on you the burden of ensuring that the form complies with the requirements, and that it remains compliant following any updates.