(1) no answer. using image drawable for the thumb, and scaling it dynamically, when it gets big it aligns its top with the top of the SeekBar view so not sure how to make that different. Padding the top will give more space for the image to grow, if there's enough screen space.
The answer to (2) is to have elements lay on top of each other, use RelativeLayout to contain all the elements rather than holding each "row of stuff" in LinearLayouts. The clipping comes from the row of stuff being in separate Linear Layouts.
So have a RelativeLayout with all the stuff and use the Layout tags to position everything like:
android:layout_alignTop="@+id/textLabel1"
android:src="@drawable/ic_action_about"
android:layout_alignParentRight="false"
android:layout_alignParentLeft="true"
android:layout_alignParentEnd="false"
android:paddingLeft="0dp"
android:layout_marginLeft="-10dp"
android:layout_marginTop="-18dp"
In the code the element (in this case SeekBar with images for thumbs) can be brought to the front with bringToFront() in the startTrackingTouch
@Override
public void onStartTrackingTouch(SeekBar seekBar) {
seekBar.bringToFront();
}