No, the timetable has six blocks for six subjects. There is no room for a seventh subject.

Yes, initially you may arrange to do so during the Drop/Add period but not for the final diploma since the 4th HL subject does not add to university applications but potentially lead to a lower IB total.

The standard 6-subject IB diploma cannot accommodate 3 sciences. A non-standard IB diploma with 3 sciences is only possible if you provide official university entry requirements mandating it. This route requires giving up a Group 3 humanities.

ESS can satisfy either the humanities or science requirement. If you've already filled your humanities quota, you can still take ESS as your science.

You'd need to drop an art, unless one of your sciences is ESS (Environmental Systems and Societies).

For finance/business, Economics and Business Management are commonly chosen, and Math AI (Applications & Interpretation) tends to suit finance better than Math AA. For medicine or other specific programs, requirements vary by country and university, so always check the specific entry requirements of your target schools.

If you're new to a language, you take it Ab Initio. If you have prior experience, placement (Ab Initio vs. B vs. A) is generally subject to evaluation by the relevant language department during Orientation Week (applies to Mandarin and other languages alike).

Students must take two different language subjects, with at least one being a Language A.

Generally 2–5 years of prior study in that language.

Yes, switching between levels is possible, subject to the relevant language teacher's evaluation and recommendation.

Yes, self-taught language options exist (e.g., for less commonly taught languages), but there is no formal assessment built into the self-taught track itself beyond the standard IB requirements.