How lucky your are to get the chance, Its a properly fantastic experience, I/we rode to the middle of France for the last one our way, wandered up to the top of a hill sticking out on the farmlands and watched the oval ripples of shadows rush across the fields 40 miles away while plunging us into eerie darkness.. silenced all of us, and the birds,just the sound of quick firing shutters.
For the actual full on Eclipse you don't need any filters, its like hundreds of times darker at this point and well within the average cameras ability. Before that though you need a Solar filter to catch the progressions, I think people also use welding glass as a cheaper alternative. not sure though.
I shot at 320mm which wasn't nearly enough, I think you'll need to find a way of getting near the 1000mm mark for a fuller frame of it all.
Unfortunately for us it was partially cloudy and none of my shots are any good, Id show you but they are film shot and I don't have a scanner. I believe digitally that you can improve cloud and fuzz problems if you bracket a few shots at different exposures and then combine somehow for best effect...
Thats all I know, it may not be that accurate.