Office Web Apps is discussed in great detail here:
HOWEVER, the hardest thing was to find out where the Office Web Apps component is hiding, so that we could install onto a new farm.TechNet just says go to the Volume Licensing Center, but fails to say what to look for!
So the answer, after much asking around, turns out to be simple. It's in the Office Professional download.
1) Log on to the Microsoft Volume License Service Center (VLSC) at https://www.microsoft.com/licensing/servicecenter
2) Click the “Downloads” tab at the top of the page, then choose Office Professional Plus 2010 or Office Standard 2010
3) Choose the desired language:
4) Choose the operating system type (Office Web Apps will only be listed in available downloads if the “32 bit” or “32/64 bit” option is chosen):
5) Click the Download button:
6) Use the Download Manager or Web Browser option to download source files for Office Web Apps 2010:
7) Make note of the Office Web Apps Setup Key which is displayed in the Special Instructions section. This key is required to install Office Web Apps 2010, and cannot be used to install other Office 2010 family products.
Now that you have it, how can you extend things? An interesting post here:
AND LASTLY!!!!!! OWA has completely separate patches from SharePoint. Every time you are installing updates, go check/search for any OWA specific patches. They are NOT bundled!e.g. 1. OWA SP1 2. WacProof-en-us.msp from Dec-11 3. WacProof-(your non-english locales).msp from June-11 4. WacWFE-X-None.msp from June 12 5. XLwacwfe-x-none from april 12