Drum parts that you can read? I'm not aware of *any* keyboard that can do that. The only keyboard I know that has a display even close to large enough to read sheet music is the Korg OASYS (have $8,000 to spend and want the best keyboard on the market? Get that).
Sounds like you want something that can read a MIDI file and play it back, with the option to turn off the drum track. Many mid-range keyboards do that. To actually see and learn the part, go buy some notation software (Finale or Sibelius; Finale also has cheaper versions that will probably suit you unless you intend to also compose complex classical works and/or want better-quality playback).
When you're talking about downloading tunes though, it's not clear whether you mean MIDI files or audio files. If you mean audio files, don't bother with a keyboard; use your computer. For one thing, technology to extract a part from an audio file is very, very new, and extracting an entire drum part, where the sounds of cymbals compared to hi-hats compared to toms compared to snare are all so different, is something that can't be done yet. That kind of thing requires the processing power of a good computer, not a keyboard. There are some keyboards that let you play back an audio file (the Roland Juno-Stage for sure, plus any keyboard that can sample audio should let you sample an MP3, or at least a WAV, though it might be awkward to play that back), but you're not going to find any keyboard now that will take an audio file, silence the drum part, and play everything else.
