Just upgraded to V10. When making a movie from stills can they be imported direct into Premiere Elements 10 from CS5 and will PE10 optomize the stills automatically?
If not, what is the best size and resolution for the stills to be imported into Premiere Elements?
PrE can only Scale Still Images automatically. Any visual "optimization" will have to be done with Effects.
However, as PrE is NOT an Image editing program, I strongly recommend that ALL work be done in PS/PSE, prior to Import into PrE. This goes for Scaling, Color Correction, Density Correction - really everything.
I take it to the ultimate extreme, where the output from PS is exactly what I want for each Image - pixel x pixel size, all CC and Density work, all Corps, everything - spec'ed. to the exact Frame Size of my Video Project. If I need to Pan on a Zoomed out Image, I will calculate exactly how many extra pixels that I need, and Scale to precisely those dimension. Some editors will leave extra pixels, "just in case," and that is not a bad idea. That is why you will see recommendations for sizes, such as 1000 x 750 for SD Projects (720 x 480 NTSC, or 720 x 576 PAL). For HD Projects, a size of 2000 x 1500 is often recommended. I take it a step further, and will output to the exact Frame Size dimensions.
Good luck, and I think that you will be much more satisfied by doing ALL Image editing, in PS first. Also, PS is a Color-Managed Workspace, where PrE is not. That can have some effect too. With Video, the only way to tell exactly what you are getting is to have a feed to a calibrated production monitor (something that PrPro allows), and even then, there is zero control over the calibration of the viewer's TV, but one has done all that they can, to insure proper output.