I get RSI from using Alt-Tab.
1) Any easier app or way to switch tasks?
2) Can I map it to a single key ?
I use Openbox as my Desktop Environment and I don't use panels much.
Openbox is fully configurable. You can map any key (like Super) or key combo (Like Alt + Space) to any action (Also works to launch apps, terminal commands...).
Install obkey and launch it to set your mapping.
Edit or create the ~/.config/rc.xml
file.
If you're on lubuntu or other distro, this may be called lubunturc.xml
or differently.
Search for A-Tab
in it and replace it by your keybinding. You can find simple and complete doc about keybindings (for special characters...) here : openbox.org/wiki/Help:Bindings, and you have a list of available actions to point to here : openbox.org/wiki/Help:Actions#PreviousWindow.
On openbox the rc.xml file can be found in ~/.config/openbox/rc.xml
There you should have a section:
<keybind key="A-Tab">
<action name="PreviousWindow"/>
</keybind>