Learn Hardcore Chinese: Chúle zhōumò yǐwài, wǒmen dōu cóng jiā zuò dìtiě dào gōngsī. - Except on weekends, we all take the subway from home to the company.

Here it means except for. The giveaway is 都 in the main clause: 除了 A 以外，S 都 VP = “Except for A, S all VP.”
For the “besides/in addition to” meaning, you’d use 也/还 instead: 除了 A 以外，S 也/还 VP.

Is 以外 required after 除了? Can I say 除了周末，我们… or use 之外?

以外 is common but not strictly required in everyday speech: 除了周末，我们都… is fine.
之外 is a bit more formal/literary: 除了周末之外，我们都…
Very concise written style: 除周末外，我们都…

What exactly does 都 mean here? Does it mean “both”?

都 means all (it covers two or more). It doesn’t specifically mean “both,” though when the set has two items it effectively means “both.” In this sentence it quantifies “all the relevant days (other than weekends)” or “all of us,” depending on context.

Is 都 necessary here? What happens if I drop it?

For the “except for …, (everything/ everyone) …” pattern, 都 is strongly expected: 除了周末以外，我们都… sounds natural and clear.
Without 都, it’s grammatical but feels less idiomatic for the exclusive reading. People often restructure, e.g., 除了周末，我们平时从家坐地铁到公司。

Where should 都 go? Could I say 我们从家都坐地铁到公司?

Put 都 after the set it quantifies (usually the subject): 我们都从家坐地铁到公司 is the safest default.
You’ll also hear 我们从家都坐地铁到公司; it’s acceptable, but the clearest placement is right after the subject: 我们都….

Why use 坐 with 地铁? Can I use other verbs like 乘/搭?

坐地铁 is the most common, neutral way to say “take the subway.”

乘/乘坐地铁: formal or written.
搭地铁: common in Taiwan and some regions; informal.
Don’t use 开 unless you mean “to drive (operate) the subway.”

Why is it 到公司 and not 去公司? Is there a difference?

Both are fine here:

坐地铁到公司 emphasizes reaching the destination (arrival/result).
坐地铁去公司 emphasizes going toward the destination (direction).
When talking about duration to arrive, 到 is especially natural: 坐地铁到公司要四十分钟。

Why is there no 在 before 公司?

在 marks a static location (“at”), but this sentence expresses movement toward a goal. For movement, use 到/去. If you want a static statement you’d say 在公司上班 (“work at the company”).

What’s the role of 从家 here? Could it be 从家里? What about 在家?

从家 and 从家里 both mean “from home”; 里 adds a slight “from inside” nuance but either is fine.
在家 means “at home” (state), not “from home,” so you wouldn’t use 在 in this movement pattern.
Don’t say 从在家.

Can I shorten this to something more natural like “take the subway to work”?

Yes: 除了周末以外，我们都坐地铁上班。
You can also keep the source: 除了周末以外，我们都从家坐地铁上班。

Is 周末 referring to any weekend or a specific one?

Without a modifier, 周末 is generic (“on weekends”).
For a specific weekend, add a determiner:

这个周末/本周末 = this weekend
上个周末/下个周末 = last/next weekend
For “every weekend,” say 每个周末.

Can I move the 除了…以外 phrase elsewhere in the sentence?

Yes:

我们除了周末以外，都从家坐地铁到公司。
As an afterthought: 我们都从家坐地铁到公司，除了周末以外。
Initial position (your original) is very common and clear.

Can I change the order with 从…到… and the transport phrase, like 坐地铁从家到公司?

Possible orders:

Most natural: 从家坐地铁到公司。
Also acceptable: 坐地铁从家到公司。
If you front the route, it’s usually part of a longer structure: 从家到公司坐地铁要半小时。
Avoid awkward splits; keep 从…到… and the verb phrase cohesive.

What’s the function of 到公司 here—preposition or complement?

It functions like a directional/result complement to the verb phrase 坐地铁 (“take the subway and arrive at the company”), i.e., manner + goal.

Are there alternatives to 都 like 全 or 全部?

Yes, you can say 我们全都从家坐地铁到公司 or 我们全部都从家坐地铁到公司 for stronger emphasis.
Plain 都 is most common and least marked.

Any pronunciation pitfalls in this sentence?

都 is dōu here (not dū).
地 in 地铁 is dì (because it’s part of a noun); the adverbial particle 地 is pronounced de in other contexts.
除了 chúle, 周末 zhōumò, 以外 yǐwài, 坐 zuò, 到 dào are the standard readings.