I have a site that I am trying to convert over to DNN.  I created it in Visual Studio and Expression Web but the friends of mine wanted an easier way to be able to edit it themselves so here I am new to DNN.  I have a million questions and things I don't understand but am wading through the manual and these forums but here are a couple of questions for now.  

• When I created this site originally I used a master page.  The reason for this is that the site www.runforfreedom5k.com has a bunch of sponsor logs at the bottom of EVERY page that change every year depending on who that years sponsors are.  Using a master page gave me an easy way to add or delete a logo in one place that would propagate to all new or existing pages.  Is there a way to do that in DNN?  I am assuming that a page template is dead info once I use it.  That is if I change the template things won't change on existing pages using that template.  
• Right now I have everything put inside an html box which is probably the wrong way to do it.  BUT, how do I do things like the countdown clock that is on that page?  It uses javascript.  Also right now it is sitting on top of a rectangular image that uses some javascript to display different images every time you go to a page.  Can I layer things like that?  How do I do javascript?  

You can see where the dnn site is as of today at http://runforfreedom5k.com.mytempweb.net/ but please don't laugh at my feeble attempts too hard!  It needs a LOT of work and this is only page one!