Well I have a confession that I only played though Mass Effect once (-- probably because it took around 20 hours the first time and another 20 hours sounded too much) and in that I made some pretty bad choices  

Well you can change your appearance and your class at the beginning of the second game. So don't worry about that. But as for who you killed, you're going to have to live with those choices.
 

To be honest, you're not missing much if you made some bad choices in 1. 
The amount of stuff that you may miss can fit into a single youtube video. not even kidding. :P

You don't really need to import your own save, there are some small advantages, but...
 
You have a conversation with Miranda Lawson and she asks if you remember what happened in the events of ME1. In that conversation you will set your backstory, so if you want to kill wrex, save ash, kill the queen, kill the council, and be an ass to conrad verner, then you can.