If you're new to emulation and struggling with downloading, you got a looong way to go.
With regards to download accelerators, DAP (Download Accelerator Plus) is a great free download accelerator, and there are a few others that will let you queue files in a list to download, but bear in mind that sites that host a lot of file content like rom sites have scripts these days that will prevent these type of programs from working. You will find most active rom sites will disable bots (so queuing will not work) and will temporarily block your IP from downloading if it detects multiple connections (which is how accelerators work).
Torrents or filehosting sites are your best bet, but we can't point you to them.