A kan titi na hango motar gaggawa tana zuwa.

a kan titi is a location phrase meaning something like on/along the road.

• a = a general locative preposition (at/in/on, depending on context)
• kan = literally top/surface, often used to mean on or along
• titi = road/street
  It’s written as three words because it’s a phrase: a + kan + noun.

Yes—this is a common confusion.

• a kan (two words) = the prepositional phrase on/along/on top of.
• akan (one word) is often used as a marker meaning usually/one (people) generally… depending on context (e.g., akan yi… = it is usually done…).
  In your sentence it’s clearly the location phrase a kan titi.

It most naturally reads as completed: I caught sight of… (often past in English).
If you want a more clearly “right now/ongoing” sense like I can see / I’m seeing, Hausa commonly uses ina…:

• Ina hango motar… = I can see / I’m seeing the car… (depending on context)

Both relate to seeing, but they’re not identical:

• gani = see in a general sense
• hango = catch sight of / glimpse / spot (often from a distance or briefly)
  So na hango motar gaggawa suggests you spotted it (maybe as it appeared on the road).

motar is mota plus a linking -r used in Hausa genitive/attributive constructions when another word follows closely.
So:

• mota = car
• motar gaggawa = emergency car / ambulance (literally car of emergency/urgency)
  That -r is very common: gidansu, matar Ali, motar gwamnati, etc.

Because Hausa marks gender agreement in the subject pronoun of the continuous form:

• yana… = he/it (masc.) is…
• tana… = she/it (fem.) is…
  mota (car) is treated as feminine, so you say motar gaggawa tana zuwa.

Yes. tana zuwa is the common Hausa way to express a progressive/continuous action: is coming.
It’s built from:

• ta-na (often written together as tana) = she/it (fem.) + continuous marker
• zuwa = to come
  So: tana zuwa = it’s coming.

zuwa generally implies motion toward a destination, and in many everyday contexts it can feel like toward the speaker (English “come”).
If you want to be very explicit, you can add the destination:

• tana zuwa nan = it’s coming here
• tana zuwa wurinmu = it’s coming to our place

The sentence is basically:
[Location] [I + saw/spotted] [the ambulance] [it is coming].
You can often move the location phrase for emphasis, and you can also front the object for focus, but the given order is very natural. For example:

• Na hango motar gaggawa tana zuwa a kan titi. (still fine)

A common negation pattern in Hausa for this kind of clause is ban … ba:

• Ban hango motar gaggawa tana zuwa a kan titi ba. = I didn’t spot the ambulance coming on the road.
  If you negate the “coming” part instead, you would negate that clause rather than na hango.