here is a two minute process to do this! if you dont have a square format image, you must have separated the portrait shots and the landscape ones into two folders and process each folder separately.
1 step create action, by going to actions, new set,new action (name these for easy reference)and press record on the new action
(while recording) open an image (pick 1st document) from the folder you want to resize, crop as desired by going to image, image size, enter desired pixel dimension press ok, type or drag watermark into document, move to correct spot, press ok, save document and save as "filename001.extension" and close, then press the stop button on actions.
2 step, go to file, automate,batch, enter the details for play: set name1, action name1
enter details of source and destination folders , choose the an option for each parameter including those in the file name panel on both source and destination folder panels, tick the override action open and save as commands boxes respectively, press ok and automation starts. You can place more folders in the first folder and process unlimited number of images for any actions you set in the above way, besides resizing and adding watermarks,you can record actions on image adjustment and tool usage!
hope it makes sense

george greco