Það snjóar, svo við förum ekki út.

It can mean either:

• It’s snowing (right now), very common in conversation.
• It snows (habitually), depending on context (e.g., climate statements).
  If you want to be extra explicit about “right now,” Icelandic often relies on context, but you can also add time words like núna (now).

Here svo is a connector meaning so / therefore / and so:
Það snjóar, svo við förum ekki út. = It’s snowing, so we’re not going out.

Svo can also be an intensifier meaning so/very (like so cold), but that use appears in different structures (e.g., Það er svo kalt = It’s so cold).

It’s common and usually recommended when svo links two independent clauses (each with its own verb):

• Það snjóar, (clause 1)
• svo við förum ekki út (clause 2)

In casual writing you might see variation, but the comma is a safe choice here.

Because Icelandic verbs agree with the subject in person and number:

• við = we (1st person plural)
• Present tense of að fara (to go) is förum for við.

So við förum = we go / we are going (depending on context).

It can mean either, depending on context:

• We don’t go out (habitual/typical)
• We’re not going out (a decision/plan right now)

If you want to emphasize a future plan more clearly, Icelandic often uses ætla (intend) or munu (will), e.g. við ætlum ekki út or við munum ekki fara út.

Ekki (not) generally comes after the finite verb and before many adverbs/objects it negates.
So the typical order is:

• verb: förum
• negation: ekki
• direction/adverb: út

Hence förum ekki út = don’t go out / aren’t going out.

Yes. Þess vegna also means therefore / that’s why and is often slightly more formal/explicit.
You might say:

• Það snjóar, þess vegna förum við ekki út.

Notice the word order often shifts: after a fronted adverb like þess vegna, Icelandic typically uses verb-second order, so förum comes before við.

Icelandic is generally a V2 (verb-second) language in main clauses: if something other than the subject comes first, the finite verb usually comes next.

• Original with svo: the second part is often treated like a following clause where við can naturally appear right after svo: svo við förum...
• With þess vegna as a sentence adverb placed first in a main clause: Þess vegna
  • förum
    • við ...

So the verb jumps to second position in that structure.

A learner-friendly approximation:

• Það: like th in this
  • ow (roughly “thowth,” but the final ð is often very soft)
• snjóar: roughly “snyoh-ar” (the jó is like “yo”)
• svo: like “svuh” (short o)
• við: “vith” (soft th at the end)
• förum: “fuh-rum” (ö is not “oh”; it’s more like a rounded “uh”)
• ekki: “EH-kee”
• út: like “oot” (long ú)