I’ve not taken time to experiment with this as I’ve always used OpenMRS on multicore machines with at least 2.3GHz of processor speed.
But during development, I’ve realized machines with less than 8GB of RAM turn to be very slow when running IDEs like eclipse and InteliJ in debug mode. I’ve had best experience with development on a quad core machines with 16GB of RAM.
As for tomcat, I have installed OpenMRS 1.x and 2.x on both Tomcat 7 and Tomcat 8 and they worked flawlessly.
OpenMRS SDK used to have issues with MySQL 5.7 but that seems to have been fixed as I’m running the sdk now with MySQL 5.7. But I’ve only run OpenMRS 2.x on MySQL 5.7. I’m not sure how OpenMRS 1.x will behave on MySQL 5.7 but it works fine on 5.6.
Any version of OpenMRS from 2.0 should be run on Java 8. OpenMRS versions below 2.0 can be run on Java 6 or 7.