Ok so I finished the game today and i knew broken steel continues the story so I have a few questions and I hope you can answer them for me.  
 
1) I saved the game when Liberty Prime is still blowing everything up before I entered the memorial. If I buy broken steel and load the game from that point, will the DLC work? or does it have to be done before you start that quest? Because I have no other save file and really don't want to start from the beginning.  
2) When purchasing Broken Steel, does the game completely open up so you can keep playing the open world and do side quests you didn't do before, or does it lock you into only the new quests for the DLC? 
 
Thank you fellow duders for any answers you can help me with. 

Well I just recently beat all the DLC.
 
Answer to #1 I think it should be ok just kind of hang back and wait till the DLC loads in (It will pop up on your screen saying the level cap has raised)
 
#2 Yes after you beat broken steel the wasteland is yours to explore

" Well I just recently beat all the DLC.  Answer to #1 I think it should be ok just kind of hang back and wait till the DLC loads in (It will pop up on your screen saying the level cap has raised)  #2 Yes after you beat broken steel the wasteland is yours to explore "

• for a second i thought that said fable 3 lol bye

#2 Yes after you beat broken steel the wasteland is yours to explore "

 I understand they said that broken steel is one of the longer ones, but as far as quests how much more does it add?  

Been awhile since since I played it, but according to gamefaqs, looks like there are 7 or 8 little quest.

Yes, but like you probably noticed you do need a save (or the worst case start over) before the ending. There's a higher level cap and missions. It's probably the first Fallout 3 DLC I got.