I follow a procedure similar to this for most everything I do with photos.I will save the photo with an added letter on the end of the filename,(such as P1010234P)so I never overwrite the original. And I use the "Save as" choice.I either create an action to save them in a certain folder or save them to the same folder they came from.
Lets say I saved them to the same folder , I will go to that folder and find all the photos with the letter I added....and move them to a folder in my documents that I may have named "To print tomorrow". There I can look at them again and if I like what I see, I use Select all and copy to your flash drive. After I am sure that went well....I can then delete the files I no longer want or in my case, move them to an external hard drive for archiving.
Maybe I should add when I first upload the photos to the computer with a card reader.....I put them in a folder with todays date , so the size of the folder is always manageable.
I use a couple different cameras so I also put the camera name on the folder I upload to. such as My DocumentD502-12-07 or My DocumentFLUZI2-12-07
I just saw you second question this should answer that...
And I would add another letter to the end of that file name I would add a R so I knew it was resized, maybe even a RS for resize small or RL for resize large.
Also there is a resizer free from Microsoft that gives about 3 options of sizes and it renames them accordingly. look at the lower right side of this page for the image resizer.