when starting out making a character. what is the basic, sort of starting out, average power level in points for a character? 150pts, 180pts, 200pts?

Firstly.. Forget the points. The ready reckoner is an okay aid, but in most cases it won't tell you how powerful something is going to be in the game. Some things are way, way stronger or weaker than their points costs suggests.. This isn't meant to be a balanced game, it's a narrative game.

So instead of thinking about it in terms of raw points, focus on what will serve the narrative best. Is the character a swashbuckling rogue trader who makes cutting remarks while exchanging flourishes and parries with his foes in close combat.. Then don't give him a bolt pistol and awesome BS. Is the Inquisitor an aging and frail psyker.. Then consider a force rod or staff instead of a more martial force weapon, or better still, keep his weapons to a minimum and make him a support concept for other characters.

Think what the character is going to be, what they're going to be good at, what they're going to be bad at, and, perhaps most importantly, what kind of games you're playing in, then start jotting down stats and notes.

Maybe post your ideas up here too..