iMovie 10 does not have all of its tools in one place. It's features can be accessed from the Menu at the top of the screen, the toolbar at the upper right of the screen, the settings button, and by control-clicking on a clip. Often there are more than one way to access a function.
The screen shot that you posted looks perfectly normal with all buttons available. The tool bar in the upper right contains all of the icons that it should. The overlay button will appear when you place and select a clip in the upper timeline above another clip. The slider and settings button above and to the right of the timeline are there. All of your menu items are there, and clicking on them will reveal numerous other functions. Some other functions are accessed by control-clicking on a clip.
So, for example, to split a clip you use your cursor to place the playhead at the point in the clip where you want to make the split, and then in the menu bar at the top of your screen click on Modify > Split clip. Or you can contol-click on the clip and select Split Clip from the drop down menu.
To crop a clip select it in the timeline and then click on the crop tool (the one that looks like intersecting angles) in the toolbar at the upper right of your screen. That will reveal a selection box with crop controls.
To adjust the sound in a clip, select a clip with sound in it and that will activate the sound adjustment icon (the one that looks like a loudspeaker in the tool bar at the upper right of your screen. Clicking on the loudspeaker icon in turn will reveal various controls whereby you can adjust the sound.
To change the size of a clip or reveal the wave forms in an audio clip, click on the Settings button above and to the right of the timeline to display a selection box where you can access those functions.
All of the above functions, and many more, are explained in step-by-step fashion in the online help menu from the link that I gave you. Within iMovie itself, clicking on the Help menu and typing in the search word will give you access to step by step instructions.
-- Rich