Sagar Hirani

They can but only to a point. If you tune your snare and toms to particular notes and make your drum play a scale, then you could create melodies on the kit along with playing rhythm. But the scope of course remains limited since the drums are make to be a percussion instrument and their primary job isn't to play melodies, but rhythm. 

To a point, yet. If you never sit down on a acoustic kit, then you will feel uncomfortable the first time you do it. The feel of both kits are very different, and dynamically, you will be used to hitting a rubber band. So your hitting will be much harder than usual. So when you switch to an acoustic kit, you might play very loudly as first because you're used to hitting rubber pads.

I'd advice if you have an ekit to practice on and regularly play on, every week or two weeks go to a studio or a jampad and book it for an hour or two just to practice on an acoustic kit. That will help you keep in touch with an acoustic kit and you will be used to playing both. 

Definition of a percussive instrument is something that you have to hit to produce a sound. So examples are tabla, cajon, djembe, dhol etc. Drums are also played with sticks and you need to hit the drums to produce a sound, that's why they're categories as a percussion instrument. 

Also, a percussion instrument does not contribute to the melody, but to the rhythm of a song. Like guitar, piano, violin a melody instruments, and not considered percussion. A drum kit is not a melodious instrument. It is majorly used to contribute to the rhythm (beats or grooves) of a song. This is the reason it's considered to be a percussive instrument. 

If you live in a place where playing acoustic drums will disturb people living in your house or your neighbour's because of the loud sound, then won't be able to practice regularly, unless you make your room sound proof.

Having electric drums solves that issue since you can connect earphones to the ekit and practice with the sound coming in your ear. Anybody on the outside will only be able to hear your sticks hitting rubber pads, which does not travel across rooms.

Also, ekits are compact and can be fit in a smaller space compared to an acoustic kit.