I can press o but it creates a new window and opens the file there. I want it to open in the same window. At least it should display on the same window each time open some file but it creates new windows for each file I open. Also is there a way to make it open as a vertical split and not horizontal split? Where can I find the complete documentation/cheatsheet of all possible commands in 'Netrw Directory Listing' mode?
For the answers to your other questions, see
for all the documentation,
for using a vertically-split window, and
for a listing of the normal-mode commands (maps).
Here is quick reference from Help
--- ----------------- Map Quick Explanation --- ----------------- <cr> Netrw will enter the directory or read the file <del> Netrw will attempt to remove the file/directory D Attempt to remove the file(s)/directory(ies) o Enter the file/directory under the cursor in a new browser window. A horizontal split is used. O Obtain a file specified by cursor p Preview the file P Browse in the previously used window qf Display information on file R Rename the designed file(s)/directory(ies) t Enter the file/directory under the cursor in a new tab v Enter the file/directory under the cursor in a new browser window. A vertical split is used. x View file with an associated program % Open a new file in netrw's current directory
In the Netwr listing press ENTER.