[kotkerk]

uploaded, Product Imported, but I don't see how to turn it on and use it.

readme file:

Install
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1. Upload all files from archive to your server via FTP
2. Import product
3. Open template newpost_attachment and find:
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document.write('<input type="button" id="manage_attachments_button" class="button" tabindex="1" style="font-weight:normal" value="$vbphrase[manage_attachments]" title="$vbphrase[add_edit_files_attached]" onclick="vB_Attachments.open_window(\'newattachmen t.php?$session[sessionurl]$attachurl&amp;poststarttime=$poststarttime&amp;po sthash=$posthash\', 480, 480, \'$postid\')" />');

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Add below:
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document.write('<br /><br /><input type="button" id="manage_swfattachments_button" class="button" tabindex="1" style="font-weight:normal" value="$vbphrase[kr_swfattachment_multiupload]" title="$vbphrase[kr_swfattachment_upload_swfuploader]" onclick="vB_Attachments.open_window(\'swfattachmen t.php?$session[sessionurl]$attachurl&amp;poststarttime=$poststarttime&amp;po sthash=$posthash\', 600, 600, \'$postid\')" />');
=========
Save template

How can you figure out which Charset you need to load?

I do not quite understand what you mean =)
if you use english lang on your forum with ISO-*** encoding, import win-1251 file
if used UTF-8 encoding - import utf-8 file