moc is about as simple as it gets. Actually playing a stream reliably will always use several sizeable buffers, likely at least 8MB before you include the size of the rest of the program. Just decoding or transcoding into a file can be done without the buffer, hence tiny footprints like faad.
Your machine might well be too lightweight for playing multiple videos, but you should look into the state of your hardware acceleration, including Flash.
It isn't right that you should gets loads of x-www-browser processes spawned though. Popunders? Iceweasel plugin containers?
CPU boost while running audio is most likely due to resampling. High quality resampling algorithms are cpu-intensive, although the defaults are not usually a problem. You can control which algorithm is used (eg. in /usr/share/alsa/alsa.conf) or even whether resampling is needed. Alsa is likely to be software resampling everything to 48kHz, while your music is probably 44.1kHz. If you have a reasonable audio card then you can just let it have 44.1kHz without problems (note that some cards won't do well with this), or possibly even just let the card do the resampling if it is really fancy.
Firefox ESR is now 31. Older versions are (deliberately or accidentally) still reporting that the up-to-date Flash plugin is vulnerable . You can disable the checking, but it is a global thing and will disable your protection from other vulnerable and malicious plugins and addons.
Before everyone gets too excited. Debian Jessie is going to ship by default with systemd configured, but it is by no means a requirement and can easily be replaced (some desktops may not work with sysvinit). Debian also ships with Gnome, but Crunchbang doesn't use it. Now systemd isn't as gross and flabby as Gnome, but we don't yet know what Janice will contain. I will miss sysvinit, it was the epitomy of what is great about Linux (and Crunchbang).
This is not new, I think? The warning is still there, but ctrl-q bypasses it. Speed and convenience, don't you know Seriously, it is deliberate and it isn't going to change.
There are a few things you can do. If it is a rare occurrence then yoiu can always restart and restore session from the history menu. If that is too cumbersome there is an addon called "Always ask". Warning, it does not play well with some other tab addons, or it didn't used to anyway. You can also take the more drastic step of disabling the ctrl-q key using one of the many addons or utilities for Firefox key management.
All sorts of ways to handle this, none of them dead simple. You might try building yourself from source. Usually the dependency is simply a build choice of the package manager rather than a necessary piece of functionality in that library version. Or you could build glib yourself and install conky manager from a package. You could even hack things a bit and build yourself a static binary that doesn't need that library, or possibly any shared libraries.
If you absolutely do need that library pre-compiled, then it is tricky to upgrade in a core library because you essentially end up upgrading to Sid. Nothing wrong with that, you might want to consider it. Or just wait a few weeks for Jessie to be released.
You can get really hacky and have two different library versions on your system simultaneously. One way is to have a wrapper script that sets your LD_LIBRARY_PATH for running conky manager. It would be messy in this case because you'll need extra versions of multiple libraries (well certainly libc, probably more). Obviously you'd have to install the libraries by hand or at least with significantly modified deb files.
Argue all you like, Australis is a step in the direction of Chrome. Fewer bars, less configurability for addons, and weird ugly dropdowns that do surprisingly little while taking up a huge amount of space. If I had a nickel for everyone who has complained that they can't see my addon icons any more, I'd be rich. Not everyone has a 24" widescreen monitor or a touchscreen.
Midori has no specific sub-packages for Midori, but obviously lots of libraries. Some of which probably aren't needed by any other package you have installed. You can uninstall these at the same time as a package you delete by using the --auto-remove option. This is equivalent to running apt-get remove followed by apt-get autoremove.
Although this is good practice and should almost be mandatory (I have a line in /etc/apt/apt.conf APT::Get::AutomaticRemove "1"; which automatically specifies --auto-remove every time I remove a package, and strangely every time I install one), won't remove every package that has no dependencies. For example Midori itself would not have any dependencies but would not be auto-removed. Only certain categories of package are auto-removed, so to be ultra-tidy you need a tool to tell you about the rest that you may or may not really need.
Network manager starts up before login (before slim) by default, but with autologin it is unlikely to be fully set up before your desktop appears. Then of course nm-applet may take a few seconds on top of that to pop up and actually say it is connected. You could slow down the login, but that doesn't really seem to be the solution you want?
You don't necessarily need the headers packages. They contain include files needed to compile source for programs that will run under the kernel.
Although you can have two different kernel versions installed, you can only have one version of the headers. Linux kernel headers are "backwards compatible, but not forwards compatible". That means that you can always use older versions of the headers and the compiled programs will (should!) run on any current or future kernel. Of course if the program requires some newer features then it may require newer headers, but in general keep the headers for your oldest kernel.
Use the PAE kernel. Although not specifically because of PAE, the non-PAE kernel doesn't support SMP which you need to use both cores.
Crunchbang runs really well in 1GB. It will get laggy if you open 200 Firefox tabs or 30 big PDF documents, but for general day to day use it will be great without any special effort.