for the containers I am not saying that the first line of text should be a h1. - the container has h1 tags placed around the title token. - so any modules that you add to the page will automatically have a header tag placed around the module title.
The DNN code that you are referring to I think was for the text html module, in the later versions of DotNetNuke you do not need to make that change as it is already done for you.
I don't understand why you need to find hacks to work in both quirks mode and xhtml transitional mode. - for any CSS skins that you create they should be using XHTML transitional mode to ensure the best compatibility for the layout interpretation of your skin in a variety of browsers. - in the later versions of DotNetNuke you no longer need to set the Doc type by altering the code in the default.aspx file you set the Doc type by including a skinname.doctype.XML file within your skin files.
In one of the free skins that I have recently released there are some hacks which are targeting IE6 and IE7 separately. - I can't remember which skin it was off the top of my head but I have a feeling it was:
FreeStyleIf you are using 4.5.3 you should only need to view the 4.5 version of the tutorials.
Hope this helps, thanks,