Thanks,
To clarify slightly, our funnel right now is Wordpress landing page with email collection form —> send a newsletter saying “buy a subscription box” —> sales page —> checkout which requires a user account registration (username and password) w/ single optin —> then sit back and wait for your box to arrive —> then an email with Links to the build instructions and tutorials page.
All build instructions and media was originally going to be a blog post on Wordpress.
So the forum is almost the final step of the process where people can freely converse about the builds and ask for help. But I imagine the meat and potatoes of the process/interaction is over on Wordpress.
Does this help you in give a suggested login choice? 
I should also mention we are only 1 month old so we have no data on how our customers utilize the website.