[xubuntu] Several problems after upgrade to 13.04

I've now got all sorts of problems after 'upgrading' (yeah - right!) to 13.04 from 12.10, including:

* Wireless connection unreliable.
* Sound not working properly, including internal mic stopped working.
* Synaptic gui can only be started from a command line.
* Not shutting down cleanly.
* Opening an 'exe' file with right-click context menu no longer working.

Is there an easy way to either fix my maimed 13.04 or go back to 12.10, without flattening and rebuilding, please?

If I have to flatten and rebuild (and I really, really don't want to!), what's the best strategy for doing so such that I preserve my data and program configuration files?

Jim