Quest'ultimo problema l'ho risolto, ma in picBuff mi genera l'errore inverso.
'-Convert pic to byte[]
Dim picBuff As Byte() = StreamToBytes(imageFile)
'-Resize pic
If targetSize = PhotoSize.Large Then
picBuff = ResizeImageFile(picBuff, 600)
ElseIf targetSize = PhotoSize.Medium Then
picBuff = ResizeImageFile(picBuff, 198)
ElseIf targetSize = PhotoSize.Small Then
picBuff = ResizeImageFile(picBuff, 100)
End If