That is not as easy a question as it seems. I have not touched InfoPath forms in 2 years so my info may be a little out of date.
1. Yes PDF forms can work inside of Sharepoint. When you click on a form they will load in Acrobat/Reader and you can fill them out accordingly. There was some support for SharePoint added in Acrobat X but I am not that familiar with that integration
2. In really depends on what they are doing with the InfoPath forms. If you need a printed representation of what you have done (s a Document of Record or a creating an official gov form) then getting the current form experience in InfoPath will be very difficult. In my experience there will be a training cost associated with changing the way people fill out the forms. Th enice thing about the PDFs is that tey can look exactly like the forms you have today ...so no training cost is incurred. There are some nice integration features that InfoPath and Sharepoint can use together but if you are not using that then both technologies can do pretty mush the same types of things. Also you will need the InfoPath client on every desktop (if I remember right).
If you have an account executive you may want to have a chat with them ...they may have additional information to help you differentiate the two.
Hope that helps
Paul
You can also read my recent blog post on the business case of PDF forms in SharePoint:
