The search spiders that index websites read only text on websites and are, for the most part, incapable of analyzing Flash or image files. So, in general, stay away from both as content mediums. Do not use Flash-based site navigation tools and stay away from creating content text that is in image form. In the case of Flash navigation, the search bot won't be able to click through to index the pages the flash navigation links to, leaving parts of your website without indexing. In the case of image-based text, any useful information and keywords you put there will be invisible to the search engine. Stick to site browsing code like jQuery or CSS and create purely text-based written content.
yes, that's true and adding alt text to every image is very important it will really effect your posts in search engine results.
Actually, using too much flashy stuffs on your home page doesn't help a lot, it is better avoid it, for better result.
Yeah. Search engines are getting smart on that too, but we never know where they would fail. So better not risk.
Using flash and text in images is fine. You just have to back it up with alternate navigation or content. The other downside of flash is that it makes a page load slowly. Since Google cares more about page speed these days, you do at least want to limit the use of stuff like that.
Images can be ok - as long as you have an 'alt' tag. However, like some others have said above, it is better to stick with mostly text for the homepage; and avoid flash. Check out my multi-author website, promoteyoursites.net for more info on SEO, advertising campaigns, link building, and generating more traffic.