You can be traced on either as your IP needs to be available for others computers to see you.
Your download speed is technically imeterial as it is the upload speed of those you are connected to that determins how fast you get what you want. As to why your friends can get faster speeds without knowledge of your eMule settings I can't tell you exactly, but there are many reasons, for example they most probably are downloading different files from the ones you are and so the sources would be different, they may connect to more sources than you, they may have more files on the go than you (equating to a fasted cumulative download speed) etc.
One thing with eMule is you should set your limits to 80% of line capacity or you risk choking your own downloads.
The ed2k network is not known for lightning speeds but more for the reliability and availability of files. You can use bot services BT for new files you want fast and eMule for older files. Just don't run both at the same time.
Again download speed can not exceed upload speed, and unfortunately it doesn't matter how fast your down speed is whiile ISPs keep giving crappy upload.