Yes you will need LCDInfo also running to get something on the screen. vis_lcdinfo.dll is a support dll needed to get the data from winamp.
First thing you want to do is download the LCDInfo package from here:
http://www.skippari.net/phpBB2/viewtopic.php?t=387
There is a proper vis_lcdinfo.dll in the /extra_dlls/ directory.
For instructions to install the vis_lcdinfo.dll file check here:
http://www.skippari.net/phpBB2/viewtopic.php?t=403
"You need to put the vis_lcdinfo.dll from the lcdinfo package's /extra_dlls/ directory to your winamp/plugins directory and set it as the current visualization plugin in Winamp. You might also want to check Auto execute visualization plug-in on play from Winamp's plugin settings."
Then you need to select the correct display driver (PCD8544) from the driver selection dialog in LCDInfo. Here's some first step instructions:
http://www.skippari.net/phpBB2/viewtopic.php?t=471
The 'default' screen for LCDInfo after you extract the files from the archive is a 84x48 pixel sized winamp screen so it should be fine for your PCD8544 lcd.
To make your own screens later you can check this:
http://www.skippari.net/phpBB2/viewtopic.php?t=386
Hope this would give you some hints, let us know how it goes...
EDIT:
And to comment on some things in your first post. No, LCDInfo is not a winamp plugin but rather a separate independent program so you shouldn't put it in your winamp directory. Of course you can put it there and it should not cause problems as long as the files are in their own directory so that they don't mix with winamp files. But the vis_lcdinfo.dll file is a winamp plugin that you should put in your winamp/plugins directory. It is used by LCDInfo to read the data from winamp.
The number you get when pressing the config button is infact the length of the currently playing song. So it's not any error number or anything like that. I was under the impression that I already fixed this for the latest versions so that this confusing number doesn't show up anymore.