Ok I'm confused. At first you said you were using DLC for RB2, then you said you weren't when I asked about the title updates? Then you ask something else about RB2 again?
Anyway, you can download title updates for any game here:
http://xboxupdates.24.tl/. I think the site is down at the moment. However, once you download them place them in the Cache folder on your Xbox HDD (partition 3). For RB2 (whether you are using this game or not I am now unsure) the songs will show up after placing the title update in that folder. Also, you only need to download the most current title update.
Yes, RB2 as well as anything else will work fine from Freestyle Dash. Do you plan on copying it to the HDD? Also, did you purchase the DLC on that Xbox or get it from "another source?" If you got it elsewhere and did not purchase it on that Xbox it also needs to be unlocked with DLC patcher or Yaris Swap before it will show up on that system.