1) To show the path of a selected file in Finder click on the View menu and enable "Show Path Bar". It will show each component of the path at the bottom of the window. You can click to navigation to any part of the path and you can Right / Ctrl-Click to see options on the part you selected
2) You can copy the path from the path bar or if you right click on a file and then hold the Option key "copy" will change to "Copy path name" for the file.
Another option is you can simply drag and drop a file onto a terminal window and it will add the path.