Need help with a plugin

[Denitz]

I would appreciate any help with this functionality:

We sell courses, so we need the user to fill course's delegates names:
Need a plugin which shows text inputs for first and last names in checkout page if a cart contains certain products.
Next these names are stored with an order and are displayed in backend.

I thought about custom field plugin, so all our products will have this custom field, but it occurs that "vmcustom" plugins can't add html into checkout page with "plgVmOnCheckoutAdvertise" event.
And I am also not sure if "vmcustom" plugins it can trigger the order save.