Sorry for the dense reply. Upgrading your items will totally depend on how much you invest into each skill. In addition to the skills you mentioned, security, treat injury, and demolitions of some level are required to make the decent upgrades.
I could be wrong, but the class won't matter as much as the level of your intelligence. The higher it is, the more points you have to spend on your skills. 14 is good to start as you will get the chance to increase it as the game goes on.