Inkscape doesn't seem to support charts or tables, so what's the best way to create a chart/table and import it into Inkscape? Excel 2013 unfortunately doesn't seem to support svg.
@Yisela recommends Gnumeric. I would also recommend looking at LibreOffice.
What I've done in the past is:
A similar approach can be taken with charts.
If you prefer to stick with Excel, at least for the charts part, you can install the "Save as PDF" office add-on and select your charts as PDF files which you can open just fine in Inkscape.
For both of these options, most of the actual content editing would take place in LibreOffice or Excel. Inkscape would really be for fine-tuning the output.
Finally, if you're working on a project that needs lots of tables and charts, you might want to invest some time in learning a programming language like R, with which you can generate publication quality charts and tables quite easily.
Since you mention Excel, something you could do is use Gnumeric to import your .xls files into it, and from there export them as SVG. Unlike Excel, Gnumeric has more export options that would allow you to create more complex elements without having to actually draw them on Inkscape.
There is also an extension for Inkscape called NiceCharts that is good for creating basic pie and bar charts. It hasn't been updated since 2012, but it seems to be working nicely.
Other options are Gnuplot (a command line - with several frontends - driven interactive data and function plotting tool has SVG output for graphs & charts) and Matplotlib (a python plotting library and can also output SVG). Finally, SVG charter is a perl script dedicated to generate SVG charts on web servers.
For diagrams, Graphviz can produce structural information as diagrams of abstract graphs and networks in SVG and other vector formats.