I have a 7Gb/month plan on an unlocked Samsung with no tab. When I upload a file over a mobile network how does that affect my data usage? Also, I'm planning to provide internet to my desktops/laptop/tablet/ipod via wifi hotspot. How does the upload and download functions affect the mobile data usage from those devices? I dont want to go over my data limit but I have enough data to not bother getting a conventional household internet plan for what I'm doing.