There are many ways to build a site and many different platforms which can be used for this purpose.I have two questions

Q 1 - Flash Templates are not crawled by Google.Is it true?

Q -2 - Does CSS Templates also have the same issue or it is OK?

A 1 - AFAIK the Spiders used by search engines rely heavily on text content when indexing sites. So I don't think it's the case that they aren't crawled at all. It's more likely that googles spiders/crawlers are unable to see much of the text/infomation contained in flash sites as much of it is embedded in .swf files rather than in the HTML files (which is where the spiders concentrate on finding/indexing information). So Flash content always seems to trip them up. However there are ways to improve SEO for flash websites.

There is a good article about SEO and flash websites here:
http://www.hochmanconsultants.com/articles/seo-friendly-flash.shtml

A 2 - AFAIK, CSS is fine. When used properly CSS can actually aid Search engines / SEO. There are a few CSS techniques that can affect your ranking in a negative manner, but generally speaking using CSS is a good thing!
Take a look at this article:
http://www.stonetemple.com/articles/css-and-seo.shtml