lets say someone starts uploading or downloading a large file and the progress is going along nicely and they accidentley close their browser
when you log back in can it start of the transfer where it was halted or do you need to upload/download it all over again?
Closing the Browser(window) terminates the upload. You have to start over.
Now i know that, is there anway to make the upload download transfers faster as i think it does it in chunks doesnt it?
Your Bandwidth is your bandwidth is your bandwidth. If you want to improve on this front check for bottlenecks, on your Serverconnection, Clientconnection and Serverperformance.