Guten Abend, ThienZ !
That's the BIOS chip, you're correct...
There is quite a few revisions of that board, http://www.asus.com.tw/support/download/download.aspx
Make sure you have correct one...
By the way, the latest BIOS updates for ASUS boards (even beta-versions, not listed on official Taiwanese site) I usually I'm downloading for German ASUS ftp site... ftp://ftp.asuscom.de/pub
But today many of ASUS servers are not available for some reasons... may be maitenance os something else...
Regarding hot-swaps and your question regarding BIOS caching - it is good to have it enabled, but many of modern BIOSes have no such an option (BIOS caching) - probably it is already enabled by default... (BIOS shadowing (into RAM) does almost the same, just only RAM is slower)... But I've never actually used that option (at least, didn't pay attention at all), and everything was fine...
Another issue - you have BIOS chip in PLCC case, so, probably you'll need PLCC-to-DIP converter (mentioned in my topic) to re-flash it in another motherboard (most of older motherboards have DIP32-case BIOSes). It is possible to make hot-swap in PLCC socket, but it is much easier (and much safer) to do it in DIP socket...
It is 2 Mbit BIOS, so, it shouldn't be problem to find the motherboard with 2 Mbit BIOS to use as a host for hot-swap...
If you cannot do it yourself, don't give up, I can do it for you , but it will take time (and money)...
Good luck!