The wp plugin to integrate discourse is very amazing and yes will be very better also to promote the forum.
This is true, but actually we don’t have an alternative, maybe when firefox accounts api will be avalaible someone will create a plugin or we can use the discourse system for authentication also on wordpress.
Akismet call an external service to check the message, that plugin use many way for have a honeypot system so it’s more fast respect to call an external service.
Contact form 7 - create custom contact form
smart slider - for quality slider images
google xml sitemap - add priority and create xml sitemap
yoast seo - the best plugin for seo, very simple and friendly
nextgen gallery - plugin for your gallery