For Work-from-home expenses. Do I proportionate the expenses or insert full amount of expenses and form calculates the amount?

You would enter the full amount and TurboTax would pro-rate it based either the area of your home or the number of rooms you used for work-related activities. Ex: You have 10 rooms in your house, but you only use 1 for business use. So if you spent $100 on electricity for your whole house, TurboTax will claim $10 as a Business-use-of-home expense. If you use the same rooms for both business and personal use, the calculation will also include the hours/days you used the rooms for business purposes.