1) For multithread fashion: YES.
Please check out this topic: Control file transfer process and SftpClient, SftpMultipleThreadsTransferFiles and SftpTransferMultipleFiles sample projects for more details on how to handle these events.
2) FTP and SFTP with long path name, says, it depends mostly on the .NET framework and OS Support.
- For .NET core: You don't need to do anything because it has long path flag for you.
- For other, please refer to https://docs.microsoft.com/en-us/archive/blogs/jeremykuhne/net-4-6-2-and-long-paths-on-windows-10 for enabling long path support on your servers (OS Support needed)