Do not attempt to indicate where you would like illustrations to be placed in your story, or what they should portray. This is the province of the editor and the illustrator. Some publishers will send you a letter or post card acknowledging receipt of your manuscript, but others will not. You may wish to include a self-addressed stamped postcard with your manuscript. A decision on your manuscript may take three months or more.
Some editors are slower to respond than others.
If you have not had a response at the end of two months, send a polite letter of inquiry to the editor asking about the status of you manuscript. Those editors who do accept multiple submissions must be told that it is such. All submissions must be accompanied by a stamped, self-addressed return envelope. The intention of a penned note on a form rejection or a personal letter from an editor is to let the writer know that the editor is interested in the writer's work. Then consider the editor's suggestions carefully.