how do scottish qualifications work

Im planning on entering an essay competition about the history curriculum in the UK and as research, I want to do a survey of peoples experience across the UK with history in schools but to do so, i need to know what level people stopped taking history. However, I'm english so dont know how the scottish education system works in comparison to the english one, so am not really sure how to ask it in a multiple choice format.
idk how well i explained that, but any answers to these would be much appreciated:
when do you start + finish studying nat 4s, nat 5s, highers, and advanced highers?
which ones are equivalent to gcses and a levels?
how many subjects do you do for each, and when can you choose to take only certain subjects (more specifically, at what point do you not have to do history)

also, is the way the work in wales and northern ireland pretty much the same as in england? i just want to make sure i don't make any big oversights lol

Im planning on entering an essay competition about the history curriculum in the UK and as research, I want to do a survey of peoples experience across the UK with history in schools but to do so, i need to know what level people stopped taking history. However, I'm english so dont know how the scottish education system works in comparison to the english one, so am not really sure how to ask it in a multiple choice format.
idk how well i explained that, but any answers to these would be much appreciated:
when do you start + finish studying nat 4s, nat 5s, highers, and advanced highers?
which ones are equivalent to gcses and a levels?
how many subjects do you do for each, and when can you choose to take only certain subjects (more specifically, at what point do you not have to do history)

also, is the way the work in wales and northern ireland pretty much the same as in england? i just want to make sure i don't make any big oversights lol

Howdy! Local English kid in a Scottish school, so I have quite a good grasp on both systems.

- Nat4 - below Nat 5 (usually sat around S2/3 if sat, not every school will do these). They aren't "registered" awards, ie your uni or workplace won't see. For what I know they are for your school to see if you are ready for nat5/prepare you for nat5. Think of year 9 assessments.

- Nat5 - first "real" exam (think of GCSEs). Sat usually in S4 (around 15/6) however, you can resit later/take more subjects later or earlier. We studied for it in S3/S4 but some schools will only study in S4.

- Highers - similar to AS-Level however a real exam with exam board and goes to your unis/workplaces (real award) - sat and studied in S5 (16/17). You can also take more highers at S6 (common occurence). Also used for 1st year entry grades at a Scottish Uni.

- Advanced Highers - similar to A-Level however slightly harder - sat and studied in S6 (17/18) and is what is used to fulfill entry requirements for English unis or second year entry at Scottish Uni.

I took quite a few subjects, so not everyone will take the same. For me, I took 8 Nat5s (bypassed maths so graded on 7), 6 Highers, 4 Advanced Highers. Most people in my school took 7 Nat5s, 4-6 Highers at S5, then either 3AH in s6 or 2AH/1H or 1AH/2H (3 subjects of any award H/AH).

We chose our subjects for Nat5s in S2 (around 13/14), Highers in S4 (15/16), advanced highers in s5 (16/17).

If you need any more info/help understanding, feel free to ask! I have no life and schools been moved online during our prelims so I will be a keyboard warrior for a month.

(edit: for reference, "sat" Nat5 in 2020, sat the SQA teacher graded paper for highers 2021, sitting AH 2022).

Thank you so much, that's really helpful!!