Unless they are small plants from recent cuttings, receiving a perfectly healthy, unblemished plant from an online source would be the exception rather than the rule.

• white spots on a couple of leaves (actually in the leaves, can’t be wiped off) These are likely the result of A) something splashed on the plant that was marginally phytotoxic, or B) symptoms of a culturally caused physiological disorder called oedema/ edema, which most often results from a period of bedding over-watered
• black marks on the stems Whenever most plants are pruned by cutting through an internode, the portion of stem between successive leaves, the internode dies back to the most distal node.

The ficus branch cutting below was severed by cutting through the branch between the leaves (through the internode). That stub will die back to the next node. If you look closely, you can see an angular collar encircling the stub at its base. The proper way to remove the stub would be by cutting at the same angle as the stub immediately above the ring. You can do that - cut all stubs back to the top living leaf. New branches will occur immediately above the leaf, just as in the ficus image I provides. It's an obligate process, meaning it WILL happen as long as the plant remains alive.

• one stem appears dead at the top with a black ring separating it from healthy green stem Not to worry. See what I wrote immediately above.

Al