LR will not read changes made in DPP (and vice-versa.) You must decide which RAW converter you want to use.
What version of LR are you using... the latest (2.1 and above, I think) have the Camera Matching profiles loaded already (nothing to import)... you access them through the calibration tab in the develop module.
Really, its up to you what you use. Obviously, LR has many tools DPP does not. Most people make the decision between the two BEFORE buying LR, as raw processing is one of its primary uses... some prefer the simplicity (and color) of DPP. With the profiles (and a little tweaking to the defaults) LR does excellent as well.
I'd say if you've already invested in LR, are using it to catalog your images... continue with that and not fragment your workflow if you don't really need to. If you're curious about DPP, go ahead and try it out (I usually experiement with each new version of DPP myself... just out of curiousity... but LR is my primary tool.)