Would it be possible to install Ubuntu 12.04 LTS to a flash drive, install all the updates and desired apps such as flash and THEN install it updates and all to another system? I'm hoping I can save a lot of time and repetition by doing it all once on the flash and then maybe applying a few tweaks after I install it on an actual machine.
Using remastersys :
You can create live iso of your existing system. so install all the required packages on your ubuntu and then take a iso using remastersys. Then using startup disk, you can create bootable usb from this iso.
edit your /etc/apt/sources.list file. Add the following line in the end of the file.
deb http://www.remastersys.com/ubuntu precise main
Then run the following command:
sudo apt-get update
sudo apt-get install remastersys
sudo apt-get install remastersys-gui
sudo apt-get install remastersys-gtk
To run the remastersys in gui mode, type the following command: