How will you be playing it on other TVs? If they have some USB ports, you'll need to know what format is supported. MP4 seems normally a good bet, so do it as AVCHD -> MP4 and save to computer. Then copy to flash drive.
I always find best saving to local computer first, as saving to flash or network share nearly always crashes PE.
You do not have to save the export to the computer hard drive and then transfer it to a USB Flash Drive.
You should be able to insert the USB Flash Drive in the USB computer port and then designate it as the Save In location in the Premiere Elements export dialog. I have not run into crashes doing that. But, do the mini test runs to find out what works for you.
As for choice on Share/Computer/, originally you did not mention TV playback. wnc_dave point is well taken. You need to check the specifications of the player to find out if the TV player supports USB Flash Drives for playback and what format on that USB Flash Drive it supports.
If file size is a consideration, then generally speaking, Windows Media is the best choice under Share/Computer....
But, the .H.264 mp4 choice under Mobile Phone and Players would be a choice. There is no AVCHD.mp4 choice in Premiere Elements 9.0/9.0.1, your version.
But, even that would be usable only if you determine that your player supports H.264.mp4 on your USB Flash Drive.
Please review and consider and then let us know if you have questions or need clarification on the above.
Interested in non-C drive saving comment, although perhaps slightly off topic. I have not had "many" crashes with USB, however have had 90% with network drives, so I find it safer to save to Main HDD. At least eliminates one possible factor when you have problems.
Here is the information on Share/Computer/Windows Media that we spoke about previously....please review it in context with the discussions here and what format to use on your USB Flash Drive with destination TV player.
Premiere Elements 9.0/9.0.1 Windows 7, 8, or 8.1 64 bit
(In this screenshot, Windows 7 64 bit)
In the screenshot, Share/Computer/Windows Media, Presets = Cable Modem, DSL
If you leave everything as is, you will get the default which includes 320 x 240 @ 30 progressive frames per second.
So, you need to customize those settings (in accord with your project settings). To do that, you click on the Advanced Button which is immediately below the Save in field. That gives you access to the Video Tab, Audio Tab, and Multiplexer Tab settings. Most of the time, the focus is on the Video Tab settings.
After you have completed customizing the export settings and you click OK to those settings, you will get a small dialog box for naming the preset. After you name the preset and click OK, your original export area will reflect your customized settings.
Please review and consider. Any questions, please let us know, including what more you need to have included in the details.