multiple machine flash drive install planning

I have two different laptops that I would like to make bootable flash drive installs for, but would then like to have at least /home on a common removable storage (either a big flash drive or USB or ethernet hard drive) to share between the two laptops (I’ll only be using one laptop as a Linux box at a time).

One laptop (Dell Latitude D410) is only 32 bit capable (Pentium M - I think there’s a 64 bit Core 2 CPU available for the socket 479, but I don’t know if the BIOS / mobo will support it). If I’m going back and forth between 32 and 64 bits, can I share /home? What else can I share - /usr or anything else?

For this purpose, would I be better off just using 32 bit Linux for both systems?

Thanks!

For ease of software management I would make both use 32bit but as far as data goes, the most important thing is that you set it to see the data partitions / folders the same way.
If you have Linux installed on both systems and are using the USB flash drives for data storage, you can have the drive mount with-in the /home folder such that moving files between the system and the external is easy without chance of messing up the hidden settings of your /home.