@Rodrigogmail Well explained. To address some of your comments:
USB2.0 will really slow you down, try to go SATA/SAS/USB3
You can have drives plotted to different accounts, but there a couple of gotcha's
Blago will mine multiple different accounts simultaneously, but they all need to be assigned to the same pool. If different pools, you need to run an instance of blago per pool. jMiner requires you run a separate instance per address
Using the same account on different PC's is not an issue, just make sure all starting nonces are unique