There's a registry entry, someone around has to know what it is, I don't off the top of my head, so for now, I offer an alternate solution.

There should be a drop-down in the top left that says "My Pictures" or something. Tap that, tap "Storage card"

If it doesn't automatically go to the right folder, you should be able to navigate your way there - you may have to tap the drop down for storage card again.

I don't know, I forget exactly how it works, I guess. I've been using arcsoft for a while now. If I need to send a picture I do it via the HTC album which shows all pictures anyway.

Edit: For the second case -- pictures tab, find the picture, tap the screen to open it full. Tap the image to bring up the bottom bar, tap the mail icon - done deal.