Learn Icelandic: Strax fer ég heim. - Immediately I go home.

This is the V2 (verb-second) rule in action! Because the sentence starts with the adverb strax (immediately), the verb fer must stay in the second position. The subject ég gets pushed to the third spot.

Could I just say Ég fer strax heim instead?

Yes, absolutely. If you start with the subject ég, the verb fer is still in the second position, and strax simply moves later in the sentence. Starting with strax just puts extra emphasis on doing it right away.

Does fer mean 'I go' or 'I am going'?

It translates to both! Icelandic does not have a separate 'am doing' form for verbs like English does. Depending on the context, ég fer can mean 'I go', 'I am going', or even 'I will go'.

Why does the sentence use heim and not heima?

In Icelandic, location words often change depending on whether there is movement. Heim implies movement towards your home (going home), while heima means you are already stationary there (at home). Since the verb fer (go) shows movement, we must use heim.