The medium is irrelevant. Be it the internet or a CD or vinyl or tape, putting out an EP of 3-4 songs and some bonus material (a song that isn't marketable, maybe a special version of one of the other songs, a remix, a video, whatever) is good promotion for a full-length LP.
I say you demo the whole album at home, pick the songs that sound good and put them on an EP as such, keep it under 30 minutes, and take the songs you don't think worked out and keep working on them. In fact, keep working on everything; what worked as your first EP release can still get better and change before it's final recording as an album.
The basic idea nowadays is to release as much as you can, it's easy to lose track of and stop caring about a new band nowadays. Even if it's a remix or an acoustic version or some kind of weird cover, release stuff, create hype, and worry about the LP when you're already famous. You'll sell more copies.