Essentially I want to add a nice "splash" page that visitors will see and can click on an "Enter" button before taking them to the index page with all of the WordPress content.
Ideally you will need a custom page template (because usually splash page has slightly different layout/design). Then create a new page, assign that page template to the new page, and make the new page as your front-page from "Settings > Reading > Front Page" menu.
Thank you so much! Does it affect SEO ranking or anything having a splash page with not much content on it coming before the index page, or does Google or whichever search engine only read what's on the index page specifically, and therefore it doesn't matter if you have one or not?
I can't comment on that because I'm not an SEO expert. But as a user.. I feel annoyed with splash page, it's so 90', lol... Really, why do you need a splash page? I'm visiting your site for the information, and I want it straight away... you distract me with splash page or popup ads then you'll lost me, I'm moving to the next site. The only splash page I can stand is the one on porn site, hahaha
HaHa. Yeah, I know splash pages can be annoying. But I just have a cocktail recipe blog and I'm a fan of creative webpages, so I wanted to design a simple splash page of an image of a bar and clever little "come in for a drink" enter button to take you right to the content. It's an experiment. We'll see how it goes.