Hello Kevin,
You can use a half year for the current year so long as you set the reporting periods as such. That way you will be able to add the opening balances so it is for the half year. Alternatively, you will need to use the journals function to account for your balances, but this will need to be done with the help of an accountant.
For your second query, you can find the Profit and Loss on Reports > Financials > Profit and Loss. In order to enter profit and loss figures, again, those will need to be done with a journal or with the Settings > Getting Started option.
When you are inputting the information, you can input the sale and bills which are still outstanding which will allow you to allocate them once you get the money from your customers or when you pay the bills.
Let me know if you need further help.
Regards,
Vanish