There are several reasons for this division. When more than one band plays in a single performance, the drum kit is often considered part of the backline (the key rhythm section equipment that stays on stage all night, which often also includes bass amps and a stage piano), and is shared between/among the drummers. Oftentimes, the main "headlining" act will provide the drums, as they are being paid more, possibly have the better gear, and in any case have the prerogative of using their own. Sticks, snare drum and cymbals, and sometimes other components, are commonly swapped though, each drummer bringing their own. The term breakables in this context refers to whatever basic components the "guest" drummer is expected to bring. Similar considerations apply if using a "house kit" (a drum kit owned by the venue, which is rare), even if there is only one band at the performance.
The next thing that you need to consider is whether the bass guitar has frets or not. Having bass guitar with frets makes it quite easier to play and one will be able to produce a more consistent tone. The advantage of going with a fretless bass is that it will produce a more unique sound. It is also best to produce the vibrato effect that you hear often in the popular musical styles like Funk and Jazz. As a beginner, you can start out with a bass with frets.
Since there are so many digital pianos worthy of your attention in this catalog, you may want to narrow down your choices using some of the search options on the sidebar. For example, if you select stage digital pianos under the category section, you'll be presented with all the digital pianos that were made for the stage. Once here you have the opportunity to drill down even further and can search by topics like number of keys, MIDI/USB Connections or by whether or not the digital piano has built-in speakers.