Interesting question.

For examples of some app specific questions and user flows, I recommend looking at this paper which talks about usability testing of specific android applications. To quote an excerpt from the paper

4.1.2 Test Questions and Testing with Users

1. Get the result of (189 + 2874) * (408 + 521). The motivation behind this question is lack of visibility of braces in portrait mode. To calculate the above expression, user either has to change the view to landscape mode or advanced panel in the portrait mode to find the braces. Before the test session users were made familiar with portrait and landscape modes in the phone but one out of five users (smart phone user) was able to figure out to use the landscape mode to enter the braces. The rest of the participants could not think of switching to landscape or advanced panel to enter the braces. All of them used portrait mode by remembering the result of the first part to complete the whole expression.

2. Get the result of the following expression: 2 (tan(45))/log 10. The motivation behind this question is the ability to slide horizontally to switch between the panels from basic to advance. There are two ways to go to advanced panel, sliding horizontally or selecting advanced panel from menu options in which the first one is easier but there is no visibility for the user to find this feature. The more visible way for the user is by going to menu options and selects the advanced panel but this makes it harder for the user as it requires switching to advanced panel several times. Only one participant among all could learn about the sliding feature to accomplish the task.

With regards to general usability testing guidelines for android apps, I recommend looking at these suggestions. To quote the article

Touch

• Sidebars are not easy to use on touchscreens.
• Fingerprints are more visible on darker backgrounds.
• There must be a way to go back or undo an action, as touching the wrong item is done quickly.
• The full screen should be used.
• Common operations directly visible on screen.
• Minimize keyboard input.

Icons & Buttons

• Buttons should have the right size and be suitable to big fingers.
• Buttons in the same place of the screen to avoid confusion.
• Natural and consistent icons.
• Buttons that have the same function should have the same color.

Menu

• Contextual menus are used very often, it should not be overloaded because it has to be used quickly.

Text

• Keep text simple and clear.
• Short sentences and paragraphs are better readable.
• The usage of headers will make a text better readable.
• Bullets for lists will make a text better readable.
• Typing text in a textbox should start with an uppercase letter.
• The font size should be big enough, not too big and not too small.

Messages

• Confirmation messages should be avoided, a click performs the action directly.
• When the app starts downloading a lot of data, the user should be warned.

Lastly I strongly recommend looking at the Human Interface guidelines for Android to ensure you can define the appropriate usability test attributes as per the proposed guidelines.

For examples of some app specific questions and user flows, I recommend looking at this paper which talks about usability testing of specific android applications. To quote an excerpt from the paper

4.1.2 Test Questions and Testing with Users

1. Get the result of (189 + 2874) * (408 + 521). The motivation behind this question is lack of visibility of braces in portrait mode. To calculate the above expression, user either has to change the view to landscape mode or advanced panel in the portrait mode to find the braces. Before the test session users were made familiar with portrait and landscape modes in the phone but one out of five users (smart phone user) was able to figure out to use the landscape mode to enter the braces. The rest of the participants could not think of switching to landscape or advanced panel to enter the braces. All of them used portrait mode by remembering the result of the first part to complete the whole expression.

2. Get the result of the following expression: 2 (tan(45))/log 10. The motivation behind this question is the ability to slide horizontally to switch between the panels from basic to advance. There are two ways to go to advanced panel, sliding horizontally or selecting advanced panel from menu options in which the first one is easier but there is no visibility for the user to find this feature. The more visible way for the user is by going to menu options and selects the advanced panel but this makes it harder for the user as it requires switching to advanced panel several times. Only one participant among all could learn about the sliding feature to accomplish the task.

With regards to general usability testing guidelines for android apps, I recommend looking at these suggestions. To quote the article

Touch

• Sidebars are not easy to use on touchscreens.
• Fingerprints are more visible on darker backgrounds.
• There must be a way to go back or undo an action, as touching the wrong item is done quickly.
• The full screen should be used.
• Common operations directly visible on screen.
• Minimize keyboard input.

Icons & Buttons

• Buttons should have the right size and be suitable to big fingers.
• Buttons in the same place of the screen to avoid confusion.
• Natural and consistent icons.
• Buttons that have the same function should have the same color.

Menu

• Contextual menus are used very often, it should not be overloaded because it has to be used quickly.

Text

• Keep text simple and clear.
• Short sentences and paragraphs are better readable.
• The usage of headers will make a text better readable.
• Bullets for lists will make a text better readable.
• Typing text in a textbox should start with an uppercase letter.
• The font size should be big enough, not too big and not too small.

Messages

• Confirmation messages should be avoided, a click performs the action directly.
• When the app starts downloading a lot of data, the user should be warned.

Lastly I strongly recommend looking at the Human Interface guidelines for Android to ensure you can define the appropriate usability test attributes as per the proposed guidelines.