Why Iranian Navy ships entering the Atlantic is a big deal

Two Iranian naval ships, the frigate Sahand and the converted tanker Macron, have reportedly rounded South Africa's Cape of Good Hope and are heading into the Atlantic Ocean. This marks the first time Iranian naval vessels have operated in the Atlantic. The ships are believed to be heading to Venezuela, potentially to offload a shipment of weapons. This development follows the sinking of the Karg, one of Iran's largest naval ships, after a major fire, the cause of which remains unclear.

What are the names of the two Iranian naval ships reported to be heading into the Atlantic Ocean?

What type of vessel is mentioned as being a mobile base?

What significant event occurred two days before the news of the Iranian ships?

What remains unclear regarding the sinking of the Karg?

What is the potential final destination of the Iranian naval vessels?