Welcome to the Q&A Forum

Just wondering about creating links. 
Is it ok to have very long links? 
Like: http://www.robotnik.com/computer-hardware-ram/8gb-ddr3-1600-desktop

Is the above too long, is it better for SEO to be more to the point?

Also

For better SEO, is it better to use hyphens in a domain name or not?

Is it better to use a dash or an underscore in file names to improve SEO? EX memory_flash.jpg or memory-flash.jpg

Or does it make no difference?