Learn Hardcore Russian: Перед вебинаром стоит настроить микрофон. - Before the webinar, it’s worth setting up the microphone.

In this sentence стоит is not literal stands. It’s a common impersonal expression стоит + infinitive meaning it’s worth / it’s a good idea / it would be advisable to do something.
So Перед вебинаром стоит настроить микрофон ≈ Before the webinar, it’s a good idea to set up the microphone.

Who is doing the action? There’s no subject like you.

Russian often uses impersonal structures where the subject is understood from context. Here, the implied subject is usually you (in general) or one:
(Вам) стоит настроить микрофон = You should / It would be good for you to set up the microphone.
The sentence stays natural without вам because it’s general advice.

How strong is стоит настроить compared to нужно настроить or надо настроить?

стоит настроить = mild advice / recommendation (it’s a good idea).
надо / нужно настроить = stronger necessity (need to / have to).
следует настроить = more formal, guideline-like (should in a formal tone).
So стоит sounds friendly and suggestive, not strict.

Why is it перед вебинаром and not something like перед вебинар?

The preposition перед requires the instrumental case.

вебинар (nominative) → вебинаром (instrumental)
So перед вебинаром literally means in front of / before the webinar (time-wise).

What case is микрофон in, and why?

микрофон is in the accusative case because it’s the direct object of the infinitive настроить (to set up/adjust something).
For an inanimate masculine noun like микрофон, accusative looks the same as nominative: микрофон.

Why is the verb настроить (perfective) and not настраивать (imperfective)?

настроить is perfective and focuses on completing the action: get the microphone set up (finished) before the webinar.
настраивать (imperfective) would emphasize the process or a repeated habit, e.g. Before every webinar, I’m usually adjusting the microphone.

Can I change the word order? For example: Стоит настроить микрофон перед вебинаром.

Yes. Word order is flexible. The most common options are:

Перед вебинаром стоит настроить микрофон. (sets the time context first)
Стоит настроить микрофон перед вебинаром. (starts with the recommendation) Both are correct; the difference is mostly what you highlight first.

Is перед always about time, or can it mean physical position too?

перед + instrumental can mean both:

Time: перед вебинаром = before the webinar
Place: перед домом = in front of the house
Context tells you which meaning is intended.

Could I say до вебинара instead of перед вебинаром?

Often yes, but there’s a nuance:

до вебинара = by the time of the webinar / before the webinar (deadline sense)
перед вебинаром = right before / shortly before the webinar (more immediate context)
In advice like this, both can work; перед вебинаром often feels more situational and immediate.

How is this sentence pronounced and where is the stress?

Stress (capitalized here):
ПЕРед вебинАРом стоИТ настроИть микрофОН.
Notes:

стоит stress on the second syllable: сто-ИТ
настроить stress on -и-: настро-Ить
микрофон stress on the last syllable: микроф-ОН