Silent or unattended installs are mostly the creator of the program's responsibilities.
For most microsoft updates/products, there are silent install options.
You might need to run a specific service or some such to push these type installs however.
To find out if firefox has a silent install, search for it on Google for example. Link to page with info on Ff silent install. A topic on the mozilla forums about it.
You will have to do this research for every product you wish to silently install, as stated, it's not a standard option for all software, and if it is, the trigger/parameter for silent installs differs for each of'em.