Regarding publishing the client, the type of errors I get are a bit strange. For example I have some images within the form (placed there by just using the Insert Picture button) that show up with the red X / image not found icon. If I download the xsn, I have to install the certificate for the digital signature, then once opening I have to confirm that the certificate is trusted. The form seems to display fine (except for weird things like the red X), until for example I click a button that has some managed code which gives me an error "could not load assembly Microsoft.Sharepoint version 12" or something to that nature..
As for the web form, I agree that the image conversion might be a good way to go, however I'm not seeing a lot of good options for doing this. I've considered putting in a hyperlink, that would be my last resort.. it gets the job done, but it's pretty lame.
What I'm experimenting with now is a web part page with two content editor web parts.. each has an iframe that will 1) Load the InfoPath form which has a static url and 2) Display the pdf preview.. tricky part might be in getting the PDF iframe to update appropriately.