Hi illop,
Thank you for your inquire.

If you by listing mean new file it is possible to just change the file. Our plugin reads the data from file on every page load so you can be sure that it will load data from the new one. One thing to note is that if you change number of columns, their type or order you will need to re-save the table first.

We have spacial column type for images. You can find more information about it in our - Documentation. To show images in the image column you need to have image URL's in that column. There is an option to show image thumbnails in column and full size images on click. For this you need to have 

http://domain.com/thumb.png||http://domain.com/fullsize.png

For testing purpose we have sandbox website where you can see and test all plugin functionalities

sandbox.wpdatatables.com

username: demo

password: demo

Hi illop,
 

Unfortunately not at this moment but it is interesting idea and I will add it in our Idea list and we will discuss implementing it in the future. You could achieve something similar with checkbox or select box by defining possible values as alphabet letters This way you can search by letter in strings