when to use -ik instead of -ak?
there is only a choice for Karaajaki although it should be Karaajuki كراجك هنا مبتدأ ولذلك يجب أن تكون الميم مضمومة
Yes, it should be "karaajuki" كَراجُكَ if we follow the Standard rules.
Shouldn't it be 'Karajak jadiida ya Samia' instead of 'Karajak jadiid ya Samia"?
Garage is male so it's male-new
Should it have been "JadidAA ya Sami" instead of "Jadid"?
"jadiid" refers to "karaaj" (and not "samia"). So, "jadiid" should be in the masculine form.