There is no mail merge built into Acrobat, you either need to implement a solution based on form fields yourself, or pay somebody to do that for you. To go directly from Excel to Acrobat, you would need to use a XFA form created in LiveCycle Designer, AcroForms can no longer access a database directly. Because Designer is no longer bundles with Acrobat Pro, and you can create AcroForms with both Standard and Pro, it does not matter which version you use.
It's usually better to do the merging of variable data and a static letter before you convert to PDF, because you get Ll the benefits of the merging application (e.g. full reflow of the document).
For more sophisticated merging in PDF, you may want to look into a true variable data solution like FusionPro.
Karl Heinz Kremer
PDF Acrobatics Without a Net
PDF Software Development, Training and More...
http://www.khkonsulting.com