Things have got much more complicated with the modularisation and the inclusion of coursework. I will endevour to explain a bit.....
For lots of subjects GCSE is just the same as you remember with the exams taking place in Year 11, this is usual in things like business studies, history etc.
Many of the core subjects have become modular. Maths exams can be in Nov, Jan, March or June and they take individual modules at each sitting. Lots of schools are now putting students in for 'early entry' English during Year 10 to give them 2 chances at getting a grade.
Science is massively complicated but mostly taken in modules from january of year 10 through until june of year 11 following the january/june cycle.
The assessments you are talking about are called 'controlled assessment' and they have replaced what used to be called 'coursework' for nearly all subjects including science and English.
In terms of marks being downgraded, that only applies to coursework and controlled assessments, this is a process called moderation. The school sends off a sample of work (usually 20 pieces for a cohort of 200 students) and a moderator at the exam board marks it to check that the marks scheme is being applied correctly by the teachers. If the moderator finds that the teachers have been too generous then they will adjust all the coursework for that cohort without even seeing the others.
The school will send you an exam timetable before each series of exams so Nov for maths, Jan, March (maths), June if she is taking exams in all of them which she probably won't be. You will receive results in the august and for the most part they will be module results. If the grade is in small type eg, a instead of A then it is a module grade which is only indicitive for that module. The overall grade will be a capital letter.
Some schools are entering in Year 9 which is quite frankly ridiculous. The government is pressing for a return to the end of 2 year assessment module, the sooner the better in my mind!