My thoughts...
Stop worrying about making a site that renders perfectly on all browsers. It's not possible. You should only care about the most popular browser's on PCs. Those being IE 6, 7 and FF 2.0.
If you want to make a site for each browser and/or operating system, almost any web language can detect a person's browser type, operating system, etc.
Like Gary said, a splash page is a big no no. People are already at your site, why do they need to enter again?
PHP was the first language I learned. I now know how to program scripts in VB and C# (ASP.NET), ASP, JSP, Perl, and Java Servlets. I can definitely say PHP is the easiest to learn. Which is why my entire site is written in PHP (b/c it takes less time to write code that works). But then again PHP IS a programming language. And if it's your first, it will take a while for you to learn it. If it helps, I learned PHP from the book "PHP Fast & Easy Web Development." IMO, the Dummy series books are terrible. I mean, how are a bunch unfunny cartoons suppose to help me learn something?
Having more than one site can be confusing, but not always. My friend Alex has about ten different sites under the aaroads.com domain. People don't seem to mind. Yet I once considered splitting my site into two different domains (one for current stuff and another for classic stuff) and people went crazy. Go figure.