Hey @Dhayden :).
1)There’s no good or bad subjects, there’s subject that are suitable for what you want to do (in uni) and ones that are not. However, note that for example if you want to study Econ in the future, universities will probably not accept you if its not HL, same for the rest. So you should try and make the subjects which you find attractive/more interesting HL.
2)I would say dont rush it/obsess over it. You’ll notice during your senior years which subjects interest you more as you gain more knowledge and then you’ll know what you want to do(hopefully). The good thing with the IB is that it offers you a lot of choices because of the 6 groups so you can make different combinations. For example, English Lang and Lit with Econ are good for Law, Biology can offer you so much on its own but it can also be combined with math etc. With that being said you still want your subjects be somewhat COHESIVE. You can do research during the summer (on unis, what each course entails, fees, employment rates of students that graduated, what professions u can get with what courses etc. and narrow your choices down so you know where to pay more attention to). Lets say that you think you would like to do something related to science a combination of Bio and Chem would give you many more opportunities than just bio (just an example).
3)I think you can do your EE essay in any subject however i would highly advise you not to (so will your school) to not do that. If your school doesn’t even offer psychology as a subject that probably means you want have a mentor for the EE(extended essay) which is super important (if your mentor doesnt suck anw). You could however do it in Biology and try to approach it from a psychological perspective too. (Careful though, if your EE looks more like a psychology EE than a Bio one that will definitely result in a low grade).
4)Your EE is basically a very short version of assignments you’ll have to do in uni all the time, so its there to prepare you. Therefore, you would preferably choose to do it in a subject that you consider taking in uni. However many students choose to do it in subjects like english where it is easiest to get a good grade (that works too!). Its structure varies from subject to subject. I did mine in Bio where the limit is 4000 words, but as I said, that varies with different subjects. Basically, you have to pick any topic you want (which your mentor approves) and write an EE for it. For example, in English you could write a comparative analysis between 2 books. Your topic cant be too broad but also not too specific, and it has to be kind of original (you can get inspiration from other stuff online, but if you do the exact thing as something you found online, that could result in a bad grade. This all may sound overwhelming but its less daunting when you actually get to it.
5)If you compare IB to AP/SATs i would definitely say its harder. But definitely not impossible. Syllabus wise it’s definitely not harder, what hard about it is that you have to multitask A LOT. With that being said i would still recommend it. (But that’s just my personal opinion, you could ask someone else and they could tell you that the IB is the worst thing that ever happened to them).
Anyway, this answer is wayyyy too long so I’ll just leave it at that. I actually need to get back to studying cause my Bio IB exam is tomorrow.
If you have anything you want more clarity on/any other questions/more information just give me your email/Insta/Facebook username and I would be more than willing to talk to you there.
Hope this helped ; )