I successfully created a new plugin and have the basic process working. The Infusionsoft API code works nicely when placed directly into the plugin folder. Thank you SO MUCH for your help!
In addition to getting this particular site working the way I need, you have opened my eyes to the world of WP plugin creation and the basics of filters, actions and hooks.
A few quick remaining questions:
1) The code you created for limiting entry types to individuals (above) – should that go into my plugin PHP file?
2) To limit the prepopulation to new records, should I use some variation of the Switch/Case code that I see in manage.php? Will this “case ‘add'” test work in my plugin, or will it only work from within manage.php? It looks like you’re setting the $action variable based on whether the $id is empty or not. I’m not sure what sort of test I can use from within the plugin.
3) Shall I go ahead and create my instructions for form entry and place them as an echo statement within manage.php for now, then transfer them once you send me the beta for Link?