There are several choices :

• Folx :

Folx is a free download manager for Mac OS X with a true Mac-style interface. It offers convenient downloads managing, flexible settings, etc. Folx has a unique system of sorting and keeping the downloaded content.

• iGetter:

iGetter is a full featured download manager and accelerator. With iGetter you can get the most out of your Internet connection be it dial-up, wireless, cable, DSL, T1 and other high end broadband connections. iGetter can greatly improve the speed of your downloads using segmented (accelerated) downloading.

• Leech (paid one) : clean UI.

Every modern browser has its own download functionality, so why should you use a separate application for handling downloads in the first place? Because Leech works better than any built-in download manager.

• jDownloader 2

JDownloader is a free, open-source download management tool with a huge community of developers that makes downloading as easy and fast as it should be. Users can start, stop or pause downloads, set bandwith limitations, auto-extract archives and much more. It's an easy-to-extend framework that can save hours of your valuable time every day!

- Fat Pipe: (free)

Most servers and internet service providers limit the speed a single connection can have. We can bypass these limits by splitting a download task up into many smaller chunks. This guarantees that you will fully saturate your internet connection.

http://fatpipeapp.com/media/demo.mp4

No, Apple doesn't get any payment this way. There are a lot of newspapers, magazines etc. providing apps which allow electronic access. If they would offer in-app purchases Apple would take the usual 30%.