Here are my suggestions for concept check questions to use:
If it rains I’ll stay home.
Is there a possibility it will rain? Yes
Are we sure it’ll rain? No
In the event of it raining, will the person go out? No
What will (s)he do? Stay at home
G is taller than P
Are G and P the same height? No
Is P the taller of the two / tallest? no
Who is the taller (tallest)? G
In the above, taller is more grammatically correct. However, English usage is changing and many people use superlatives where 2 people or objects are being compared. By using tallest, you will avoid having the same language in your concept check questions as you have in the original sentence.
By 4:00 he will have been working for 6 hours.
What will he be doing at 4? Working
When did / will he start working? 10.00
Is the work / will the work be interrupted? No
In the last 2 questions, choose the tense according to the time it is when you are asking the questions.