Rendering speed is very dependent on system setup, hardware, tuning, etcetera and on the codec used in the source material. Therefore it is impossible to say whether that is normal or slow without further details.
Look here: Some suggestions and answer at least the 16 questions at the end of the Wiki article. Second suggestion is to run the http://ppbm4.com benchmark and submit the results to Bill (and possibly post them here as well) so you will get a feeling for your systems performance in relation to other systems.
CS4 is a 32 bit application (apart from PS Extended, which is 64 bit) but runs great under Win 7-64. CS5 will be 64 bit only, but whether you will really profit from that with only 4 GB of memory remains to be seen.
For specific ME editions contact Adobe. I just don't know.
Welcome to the forum.
1. If your sequence settings match your footage there should be no rendering needed until effects are applied, speed is changed, etc. What video format and codec are you editing?
2. Premiere Pro is a 32bit application, but is optimized for 64bit systems. After 3-4 GB of RAM is used, the limit of a normal 32bit app, Premiere will startup a new process that allows another 3-4 GB of memory, and so on and so forth. The next version of Premiere will be 64bit.