I have a search widget in my Action Bar like this:

(1) How do I change
You can change the style of the searchview. Here is some code I used to tweak the edittext, the voice icon...
SearchManager searchManager = (SearchManager) getSystemService(Context.SEARCH_SERVICE);
SearchView searchView = (SearchView) menu.findItem(R.id.menu_search).getActionView();
searchView.setSearchableInfo(searchManager.getSearchableInfo(getComponentName()));
int searchPlateId = searchView.getContext().getResources().getIdentifier("android:id/search_plate", null, null);
searchView.findViewById(searchPlateId).setBackgroundResource(R.drawable.textfield_search_selected);
int voiceSearchPlateId = searchView.getContext().getResources().getIdentifier("android:id/submit_area", null, null);
searchView.findViewById(voiceSearchPlateId).setBackgroundResource(R.drawable.textfield_search_right_selected);
// change hint color
int searchTextViewId = searchView.getContext().getResources().getIdentifier("android:id/search_src_text", null, null);
TextView searchTextView = (TextView) searchView.findViewById(searchTextViewId);
searchTextView.setHintTextColor(getResources().getColor(R.color.light_grey));
[edit] A more complete answer is available here : Changing the background drawable of the searchview widget