An 808 is originally from a Roland TR-808 Drum Machine, but has evolved tremendously over the years. It is a hybrid of a kick drum and bassline in one sound, and is absolutely necessary to master to become a good beatmaker.
ROMplers are preset-based virtual instruments (synthesizer) that allow beatmakers to select high-quality presets FAST, without knowing sound design, to focus on creating catchy melodies easily.
I think FL Studio is the BEST DAW for making beats in terms of price and workflow. It specializes in MIDI and its Piano Roll is AWESOME to use. It is music production software that beatmakers use to create beats through MIDI or recording audio.