I think you can do everything you need to do with the image block.

"need to use an external tool to make images," - what external tool are you using to make the images?

"no 'hover effect'" - just don't set an 'image-on state' when using the image block if you don't want any hover effect on your button.

"mainly I cant use it for other actions like "download file"" - If you want the button/images to download a file on-click, just set the link to the location of the file you want users to be able to download
e.g.http://www.mysite.com/files/1234/2345/1234/myDoc.doc...

Thanks for the answer.
About the 'external tool' : I would say that I need to make (or found) an image with 'download' text and import it. It would be more convenient to have a 'button block' with text editor and parameters for the look.
I look the other points...

One option (at least for linking files) is using the File block. You could either overwrite the view.php for the block, or create a series of block templates if you wanted to have different styles.

In these templates you could set up the html you need, with appropriate classes and then add some CSS for styles. All you're really need to do is add a single class to the link the File block generates really.

In terms of CSS, there tons of examples of styling links as buttons on the web. You could even use something like this to generate your CSS:http://www.cssbuttongenerator.com/...

Then you can add a file block, pick a file and then change the custom template to change the look between your presets.

Good idea, i'll try it and make a report here.