I see this is your first post so you're forgiven for not realizing this thread was started 8 years ago then resurrected in 2017. Note the post before yours is February 2017. I haven't seen most of these people on the forum in years.

Your question is very common and it's very easy to answer. Get a tablet either Android or iPad. Both can store and playback MP3's or pure wav's. The wav's take up a lot more space while the MP3's are compressed. Don't be worried about that MP3 still sound great. If you ever listen to Youtube music, Soundcloud, iTunes etc they're all compressed too usually more than an MP3 is. Your phone has the same capability as a tablet but you'll be happier with the bigger screen on the tablet. Sound goes through the headphone out with an adapter cable so it can plug into your PA. As for apps for IOS there is Forscore:

https://forscore.co/about-music/

For Android there's Mobilsheets:

https://www.zubersoft.com/mobilesheets/

These let you create setlists, you can go from one song to the next with a bluetooth footswitch if you don't want to mess around with your finger on a touchscreen and both can link up to backing tracks so when you change songs both the leadsheet and backing tracks are ready to go.

If you already have a laptop you can use that as well but a laptop does not have easy access to these live performance apps you can get with IOS or Android. I'm sure there are probably DJ programs (not apps) for that but I'm not familiar with them.

Bob

Biab/RB latest build, Win 11 Pro, Ryzen 5 5600 G, 512 Gig SSD, 16 Gigs Ram, Steinberg UR22 MkII, Roland Sonic Cell, Kurzweil PC3, Hammond SK1, Korg PA3XPro, Garritan JABB, Hypercanvas, Sampletank 3, more.