I am not sure what is the exact issue is but you may try the workaround by directly copying you webpart ASPX and CS files from VS project to EP folder which is located "C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\14\TEMPLATE\LAYOUTS\ep\".
Or have you tried deploying it directly from AOT ?
Second error you share about Webpart not deployed occurs when there are some issues with Webpart.