in regards to getting a lower latency, this is pretty much wholeheratedly reliant on the computer.
not sure how software affects this. presumabley badly made software will
cause latency... reaper isnt badly made tho
.
you can get DSP based recording systems & sound cards, but they are (for good ones) £1200+. there will still be playback latency, but monitoring doesnt have to make a round-trip.
hope this helps & doesnt confuse