I am using Wordpress and I am trying to create a splash page that users will hit when going to my webpage before going into my blog.
My first question is what is the best way of creating this splash page?
My second question is if I created this page is it going to prevent search engine crawlers from hitting my site and seeing new content has been added to my blog now that the first page it hits is this splash screen?
Assuming you have a link on the splash page that will let users skip the splash page and go straight to the actual content, which is generally considered good form anyway, Google should be able to find it. I'd question whether you actually gain any value from the splash screen, though; they tend to annoy the people I know.
First, I'd advise against splash pages. Not for any technical reason, really. I recommend against them because they're a design staple from 1997 -- your readers don't like them.
Second, if you're going to skip over that advice and include a splash anyway, then recognize that you're trying to have your cake and eat it too. If you don't want search engines to overlook your blog page as your first page, don't make your splash page a separate page. Make it a separate DIV that is presented to the user via Javascript -- then, search engines get the blog page with all your content as well as the splash presentation.
For the 1st question, you can use the inbuilt wordpress function to create a splash page.
There is an option in settings -> reading to set a static front page. Set that to be a wordpress page within your site.
If you want a true splash page i.e. without your nav / banner etc, then you need to apply a template to that page. The page template is a wordpress feature that allows you to choose that a page be styled in a particular way. Rather than hooking into all the wordpress features, your template should simply display your splash image and then link to your main 'posts' page.
As for how this affects your search scoring I have no idea, but the sites that I've had to use this on (I don't much like splash pages) are admittedly niche areas, but all come #1 in Google, so it isn't being detrimental to them