Why a tablet?

I'm legally blind but not totally. I cannot see to read the small screens on anything big the bigger Samsung Galaxy Note and those are quite costly for me. I've been shopping for the right 7" mini-tablet to use with a Skype app to make my calls. I need one that can use a mobile phone access card in case there is no public WiFi handy. I also want one that has an SD card slot and a USB that can handle a thumb drive. I would need a Bluetooth keyboard for it because you just can't feel the 'keys' of an onscreen keyboard. With a keyboard and an SD card or flash with NVDA, Non-Visual Desktop Access app, I'd have the same controls I have on my desktop computer. I also intend to use it as a reader and music player. I may use it for FB'ing or emails, but to a lesser extent.