How long have you used this DS708? In most cases, it is occured because the card is read and written too many times.

Yes, you can make a larger capacity SD card. I would suggest you find a Sandisk, class 10 card. 8G, 16G, 32G are all OK. Just copy all files in the old card to the new card. ..If you fail to copy the files from your old card to the new card, then maybe you should think about there is something wrong with the old card.

It is impossible to send you the contents. Every card is correponding to one machine. ..you can update the whole contents through Internet.

Yes.