If you press āGā on your keyboard (alternatively click the little down arrow next to your viewport options (ie - perspective) and click Game mode), it will hide icons. Hope this helps!
No problem! By stretching the screen, do you mean having the editor viewport fullscreened? If so, press F11, or alternatively, click that same drop down arrow from the previous post and click Immersive View. Otherwise, you can resize the viewports by clicking and dragging the edges of each panel to whatever size you like best.