Short answers, pulled from the story.
ALMA is an astronomical interferometer of 66 radio telescopes situated on the Chajnantor plateau in the Atacama Desert of northern Chile, at an elevation of 5,000 meters. It observes electromagnetic radiation at millimeter and submillimeter wavelengths and has been fully operational since March 2013.
ALMA cost approximately 1.4 to 1.5 billion US dollars, making it the most expensive ground-based telescope in operation. By comparison, various space astronomy projects including the Hubble Space Telescope and the James Webb Space Telescope cost considerably more.
ALMA is a partnership among Europe, the United States, Canada, Japan, South Korea, Taiwan, and Chile. In Europe, the project is led by the European Southern Observatory; in North America by the National Radio Astronomy Observatory; and in East Asia by the National Astronomical Observatory of Japan.
ALMA produced the best submillimeter-wavelength image of the Antennae Galaxies in 2011 and revealed unexpected protoplanet formation in the disc around HL Tauri in 2014. It also participated in the Event Horizon Telescope project, which released the first direct image of a black hole in 2019, and contributed to a controversial claimed detection of phosphine in Venus's atmosphere.
Two custom 28-wheel self-loading heavy haulers, built in Germany, transport the 115-tonne antennae. Each vehicle is 10 meters wide, 20 meters long, and 6 meters high, and is powered by twin turbocharged 500-kilowatt diesel engines. Both transporters were delivered to Chile on the 15th of February 2008.
The Atacama Compact Array is a subset of 16 closely spaced antennae, consisting of four 12-meter dishes and twelve 7-meter dishes, provided by Japan. In 2013 it was renamed the Morita Array in honor of Professor Koh-ichiro Morita, the Japanese ALMA team member who designed the ACA, who died on the 7th of May 2012 in Santiago.