CONTROLLERS, single method or different methods for different actions?

Personally I think it is not a great idea to have sequential ids anywhere, as they are easy to guess or programatically run through, not in forms or urls or anywhere. Except of course in trivial matters, or perhaps where you are using say a page id, but even then, you should use a page url code and decode that to a page id so the url is nicer.

As for the colour removal, I would do the customer form as a normal form, but deleting and adding colours as a javascript function, so when the user deletes a colour it just pops off the screen (with a 'saving changes' pause in the middle - I always love using those animated loading gifs), without the user having to refresh the page for such a minor thing.

Alternatively, make the 'Edit Colours' a seperate form altogether. It is just a matter of user interface design. For the user sometimes doing this in a blocky way can be easier to follow. "How do I change my favourite colours?" "Ah, here is a big button that takes me to a nice clean screen that enable me to do that".

For me, for speed of coding I would do the blocky multi page approach, for quality experience I would do the javascript approach. Personally I try to avoid using 'flags' in hidden form fields as much as possible.

Hope that helps,

Paul.