File association hassle is tedious. If you're happy to fiddle, then here's how I would try to fix it:
Windows Explorer-->Tools-->Folder Options. Click "File Types" tab. Find the "PSPIMAGE" extension from the list; click the Advanced button. From the actions list, click Open, then Edit. Note all of the settings in each of the boxes (perhaps cut and paste them to Notepad temporarily).
Cancel those two boxes, then find "PSP" from the extensions list. Click the "Advanced" button. In the actions list, if "open" is not in bold, select and then click "set default". Next, click "Edit", and copy across the details that you saved in Notepad. Click OK to clear each dialogue box. You should now be able to double-click PSP files.
Re your Outlook Express problem: create a new message to your group; click save, then close it. The new message should be in your draft folder. Within that folder, make as many copies of the message as you like. (Click the message, then Ctrl-C, Ctrl-V.) To send a message, double-click it from the drafts folder. It should definitely have a "send" button.