-We have Direct TV, with a DVR receiver. What changes are needed to receive HD channels. Any up-front costs?

You will need a High Def receiver and Hi Def programming. Call Direct TV about deals and promotions. You can count on some charges.

-When using the SD slot, how does one change pictures? With the remote?

This TV cames with a fine manual.

-What HDMI cable will be needed?

You can use Component cables or HDMI depending on your receiver. Do not waste the money on very expensive cables like Monster. Sams club has some nice ones for about $20.