Not sure that my answer will help you, but hopefully it will...
To change the name of a router, you must have your router powered off (compulsory), than right click on it, select configure and then click on the actual router name (R1 for example). There, you should be able to configure the name, as well as other parameters (image, slots,...).
For the idle-pc, I would recommand to run it again router by router (only one at a time) and try different values, you should find one that will give you less than 1% usage (make sure that your CPU usage is null or very low before running any router). Don't use values from previous version of GNS3, the dynamips has been updated, it could behave differently I suppose.
New to GNS3 / working on network design mainly
Running : GNS3 1.0beta3 All-in-One / Wireshark 1.12.1 / VirtualBox 4.3.16 / Widows 8.1 and 10 / T430s 8GB RAM
Sorry for my poor English level