Short answers, pulled from the story.
The current Baroque cathedral was built between 1614, when Archbishop Markus Sittich von Hohenems laid the cornerstone, and 1628, when it was consecrated on the 24th of September. The site has held a cathedral since 774, when Saint Vergilius constructed the first Dom.
Santino Solari designed the current cathedral by dramatically altering an original plan drawn up by Italian architect Vincenzo Scamozzi. The project was initiated under Prince-Bishop Wolf Dietrich Raitenau, who commissioned Scamozzi, and completed under his successor Markus Sittich von Hohenems.
Yes. Wolfgang Amadeus Mozart was baptized in Salzburg Cathedral on the 28th of January 1756, the day after his birth. The 14th-century Gothic baptismal font used for his baptism is still present in the cathedral today.
In 1944, a single bomb fell through the central dome of Salzburg Cathedral, causing significant damage. Restoration was completed by 1959.
Salzburg Cathedral has seven ringing bells, including two bourdon bells. The largest, Salvator, cast in 1961, is the second largest bell in Austria after the Pummerin in Vienna. Two bells, Maria and Virgil, date from 1628 and were cast by Wolfgang and Johann Neidhart at the cathedral's consecration.
The Maria Immaculata is a marble and cast-iron column in Domplatz, the square in front of Salzburg Cathedral. It was commissioned by Archbishop Sigismund von Schrattenbach and created by the brothers Wolfgang and Johann Baptist Hagenauer between 1766 and 1771, modelled after similar columns in Vienna and Munich.