In the preferences dialog, under the “Image” tab, disable “Allow enlargement of image for zoom to fit”.
Use the “-r” command line option to send commands to an existing Geeqie, for a list of commands supported by the remote switch run:
geeqie --remote-help
The delay can not be set when used with the standard -s command line switch, as -s uses the delay stored in the configuration file. For this use the remote command -ss to start the slide show after setting the delay with -d, the order of the command line is important, for example a 12 second slide show delay:
geeqie -r -d12 -ss
Note that if geeqie is running prior to this command, the slide show should also be stopped prior to changing the delay:
geeqie -r -sS -d12 -ss
Geeqie is an image viewer. There is, and never will be, a plan to add editing features. I recommend gimp for image editing.