I am not completely sure what exactly are you trying to achieve, and what do you mean by "sidebars", so i cannot really give you a solution for your problems, but I will try to provide some pointers with hope that they will turn out helpful.
First, the wrapfig package, as well as all other LaTeX packages providing a way to wrap text around figures, does not play nice with lists. That fact is well known and even mentioned in the wrapfig documentation.
XeTeX will not help you with layout issues. XeTeX is a TeX engine that allows you to use your system fonts in your document, but it provides no layout macros of its own. Instead, you use it with other formats and macros, such as LaTeX and ConTeXt.
ConTeXt may indeed be a good choice for you. It is in general much more flexible than LaTeX for creating different page layouts, and it has a build in mechanism for placing graphics at various locations on the page. Its lists work generally well with text wrapped around figures. However, it is different from LaTeX, it has somewhat different conventions and syntax, so you will have to learn new things if you are used to LaTeX.
If you want to stick with LaTeX, you have several options. There are several packages that place material at specific locations on the page. Perhaps the most powerful is the pgf package. You can also create complicated custom page designs with the flowfram package. I suggest you look at the documentation for these two packages and see if they solve your problem.
