Thank you very much for your consideration. Three or four months is a reasonable time to wait. All you need to do then is either write to or call the editor and ask if you can check on the status of your manuscript. No editor should be offended by that. A first novel usually gets an advance something in the area of five thousand dollars.
Royalties depend on whether the book is hardback or paperback.
Royalties for paperbacks are four to six percent of the cover price. Royalties for hardback are around ten percent of the cover price. When you have a contract to negotiate. Use a line of prose, not a line of dialog. Now flip through a bunch of pages again, counting the average number of lines on each page.