Quoted from the website:
Please note that Practice Maths (formerly Master Maths) and multiple choice questions are not taken into account.
If you search for practice maths or master maths on isaac physics, you will find some gameboards that aim to prepare you for the A-level exams. But SPC wants us to go further than that, so I guess questions won't count if you find them by this way.
I'm not sure about your second question. Saw one person from previous threads say that counted as you doing two questions and another person said you couldn't just add up questions of different levels because there are overlapses. Personally I think the rules won't be that strict because judges will have a hard time figuring out how many questions we do counts unless isaac physics has another way of progress monitoring that is not transparent to us.
How many questions have you done so far?