Early Access Release Day Content
Keep in mind there will be new stuff added, but it wont be a huge full "release". Big updates like tomorrow's are planned to continue throughout early access (approximately every 1-4 months depending on the complexity of the roadmap objectives tackled).
Pricing
Since there's still a long roadmap ahead and the workshop is nearly empty as of now. The game will start with a base price of 5.99 and go on sale frequently(35% off) including tomorrow's release day. This game will forever be a one time purchase and there wont be any add-on/DLCs or anything like that.