Yes man of course it's tough lol. I got 80 in chem because of that. I'm just saying, try to stick to text, and if you can't, then write the reactions clearly and properly. But yes, if they ask you like, give a method to synthesize this product, then don't write anything that's not in the book. They will show you no mercy.
And yes all calculations must be done by log. Like even the simplest ones, except normal addition subtraction. Make a margin on the right side of the sheet and do calculations in pencil in the margin, so that examiner knows you have used the log book.