Welcome to SimplePortal!
There are a lot of options with SMF and with SimplePortal, so there is a lot to learn.
There are many themes available for SMF. Please read about themes, and see the long list of available themes, at simplemachines.org. It is also perfectly possible to create a new theme as a copy of an existing theme, and just change some colors by altering the CSS and/or the image files that go with the theme.
In general, you will have fewer headaches if you leave the default theme alone, except for the changes mods make to it.
There are a couple of gallery mods available for SMF. You can find them at the simplemachines mods site. One of them is even free (though only available for download from the author's site) and comes with a converter for converting from some other galleries.
There are a couple of "auto-embed" mods available at smf, for embedding audo, video, gallery images in posts. One of the gallery mods, AEVA media, even includes the auto-embedding feature in the mod for convenience.
SimplePortal's RSS block works well for many RSS feeds. And SMF has a way to turn your forum or any board into an RSS feed. And there are many mods to extend these SMF features.
You have probably already discovered that SimplePortal comes with several simple blocks to display many types of stats. You can learn a lot by trying these out. You cannot break SimplePortal by playing with all of the settings.
The SimplePortal documentation may help some:
http://simpleportal.net/index.php?action=docs So I think it is fair to say that SimplePortal + SMF is a combination that can do a lot of what people ordinarily want on a website. I cannot say if it can do it all -- I cannot view your website
www.kissradio.biz or the forum.