Organization/coding advice – custom post types

I need some advice on the best way to proceed:
Let’s say I have a series of manufacturers (entered in a “manufacturer” custom post type with custom taxonomies) who each make a series of products (entered in a “product” post type with custom taxonomies)

1st question: How do I tell wordpress to associate a manufacturer custom post type with the associated manufacturer’s product custom post type? I’ve thought of a few different ways – taxonomies? – but not sure which is best.

2nd question: I want each manufacturer page to display all the custom post type info for the manufacturer but just the titles of the custom post types for that manufacturer’s products (the user can link to the full product description). What’s the easiest way to do that?

Please don’t tell me to use a plug in – I hate plug-ins