To record guitar along to a backing track is simple, and surprisingly passable, just using an iPhone's inbuilt mic and free iRig Recorder app.
To add further instruments recorded separately I tried lots of different methods. Direct i-interface from about £30 upwards lets you connect direct to I-device and add effects and garageband software. PC/Laptop connection using Cubase/Reaper gives great versatility but is not for the feint-hearted and I got fed up with hum, battery life and gave up.
For ease of use and great sound I bought an 8-track recorder. I could then load a backing track or actual band song in stereo I wanted to play over which goes on tracks one and two. While playing tracks 1 and 2, I would record guitar on track 3, bass on track 4, and my wife would then add Yamaha drums on track 5. Further guitar on tracks 6 and 7 covering up mistakes on earlier track! Got daughter to sing occasionally on track 8 if I was lucky. Also guitar sounds/amps/effects are inbuilt.
Your e-drums would go directly into the Line input. My Zoom R8 allows direct guitar and bass interface, powered or non-powered mics and drums via Line. It also has two quality mics inbuilt and I now record from my Blackstar rather than direct input.
Then I play back pressing Master Record (and turn off backing track) and use mechanical sliders on the 8 tracks in real time to raise or lower the sound. The mistake say on track 3 would be lowered and track 6 or 7 would blend over it. The mastered recording can then have a choice of hall acoustic added and it saves to an SD card ready for inputting to PC and converting to mp3.