Yes, I would highly recommend an email preference or subscription management center. This would be your hub for opt-in/out activity as well preferences. I'd suggest having this built before you send out the mass mailings.
As far as prioritizing the order form, we require that our forms collect data in a certain order as laid below. This ensure we capture critical information as early as possible, then add to it through continuing nurture and qualification.
Order of Data Collection ("**" denotes required field):
**Email
**First name
**Last name
**Country
**State
**Product interest
Company
Revenue
Mission profile
Aircraft model
Title
Purchase timeline
Aircraft usage
Industry
Mission interest
We do not use Smart Lists to move people around, we have programs/campaigns set up that does it automatically. For example, we need to assign custom account owner fields based on where the prospect resides, meaning state and country populated fields are very important. Once we have that, Product Interest is critical as that custom field is used to route the prospect into the approrpriate nurture stream. We also use Revenue Cycle Analytics, or more appropriately for this, Revenue Cycle Models. These models are configured to specify where each lead is in its lifecycle which affects scoring and progressions.
In your case, you could use custom fields to define specific email preference such as a newsletter, particular product or territory in which you could flow that lead to a particular membership of an engagement stream. The campaign program would route the lead the appropriate stream based on their selection. No need for lists to do that.
Progressive profiling in forms allows you to ask those few key questions you need prioritized up front. The fewer the questions asked in a form the better. Each additional connection with that prospect then only shows their email address at the top of the form, then asks for additional info the system doesn't already know. For example, if we already have their email, name and country, the next form fill will ask for Product Interest, Company or Revenue. Assuming they leave cookies on their machine, their email address will prepopulate on any subsequent form visits.
I hope my ramblings are making sense to you.
Mike