It just seems like a very daunting game, would it be easier if I tried to play the first two in the series first?
This is a general answer rather than being specific to Disgaea.
From my experience of other game "series" you can play a sequel without having played the original. The first level(s) are usually easier and introduce you to the characters and their abilities - after all the writers can't assume that you've played the original. All games seem to have these "tutorial" levels.
What you might find is that, if you had played the original, you pick up the moves etc. more quickly, thus allowing you to complete the early level(s) more rapidly and get onto the meatier levels sooner.
Having a knowledge of the characters might make it easier to identify enemies and their attacks - but again you'll soon pick this up as you play.
Disgaea 1, 2 and 3 all have their own main story-lines (to the point where you actually don't miss much if you haven't played a prior game). Once you get into the post game you can unlock characters from previous NIS games, but knowing their story isn't important to doing so (note: I've only unlocked all story characters in Disgaea DS [D1 remake], and a few of the characters in D3, I haven't played D2 at all).
Also Disgaea 1 and 3 play fairly differently.
To my knowledge no NIS game shares main characters with another.