HC Encoder is a great free mpeg2 encoder, with extremely professional results, comparable to Cinema Craft Encoder.
For HD content, you will want to export from Premiere in the Matrox HD MPEG2 I-Frame codec in the same framerate/resolution as your source footage. Bring that into a program like Virtual Dub and Apply a resize filter using the Lanczos3 algorithm, or if you use AVISynth, use the Spline32Resize algorithm.
As for Blu-ray Encoding, I typically do everything in h264. Since Encore can be picky about Blu-ray compliant files, I let Adobe Media Encoder do those. Matrox has a new product called Compress HD which does faster than realtime h264 encoding from within the Adobe Media Encoder. You might want to look into getting that.