File ▸ Export ▸ PDF… exports a PDF with presets for print and screen; PNG…, JPEG… and TIFF… export rasters at the resolution you choose. File ▸ Save a Copy… (Ctrl+Alt+S) writes an IDML copy for the other layout applications.
File ▸ Print… (Ctrl+P) and File ▸ Print Booklet… for imposed booklets; File ▸ Page Setup… opens the Android print dialog, where the paper is chosen.
Master Page draws the pages exactly as it exports them to PDF and hands that PDF to the Android print service, so every printer Android can print to works, and so does Save as PDF. In the print dialog choose the printer, the number of copies, the page range and the paper size. Print Booklet… first imposes the pages into a booklet, then prints it the same way.
Window ▸ Output ▸ Preflight (Ctrl+Alt+Shift+F) lists problems such as missing links or overset text; Window ▸ Output ▸ Separations Preview (Shift+F6) shows the inks one by one. File ▸ Package… (Ctrl+Alt+Shift+P) collects the document, its links and fonts in a folder you choose.