Well, whenever you build an InfoPath form in Visual Studio, you have to package it and deploy it, so I imagine you can do it with a regular form, but I don't know the steps. I still needs to be published so that the template knows its references and so that it can be uploaded to Central Admin - can't upload templates that weren't published as administratively-approved. That would be the only way to deploy as a solution is if it were published as an admin-deploy type.
As for InfoPath - it's just part of the Office suite. It doesn't have to be installed separately or anything. Everyone should already have it by default unless they chose a lower suite that doesn't include it. With 2003, just about everyone had it, because it was included in the suite most organizations bought. In 2007, it's part of the Pro Plus, Ultimate, and Enterprise suites - this stuff is usually driven/governed by the Enterprise Agreement. InfoPath isn't treated as a separate application that must get installed and approve - it's just a built-in part of the Office suite. Sometimes, it's even part of the suite an organization has, and they don't even realize it, because the IT team didn't check the box for it to get installed when deployed. That happened at my current gov't client until I told them it was an extremely valuable tool that they had already paid for and should install by default, which they do now.