I work on the engineering side, rather than the project management side. The two EHT telescopes that I work on are in Arizona, although I build some of the hardware that's being taken to the South Pole Telescope. It's getting improved to be a part of the EHT. One of the Arizona telescopes is a prototpye ALMA antenna that we just moved here from New Mexico last year, and got working a month ago.
Observations are typically done in March/April. This gives good weather at the many sites involved. The typical run is a week, and they try to get several 10-minute recordings during that time period. The data is recorded at 1 Gbyte/sec onto banks of hard drives, then shipped by FedEx to MIT for correlation. (I don't know if a FedEx truck makes it to the South Pole every day.)
The frequency used for most observations in in the 1.3mm band. The baselines are intercontinental (Arizona, Hawaii, Chile, hopefully Antarctica), up to 5000 miles. The goal is to actually get fringes between all stations, although that's not always possible due to weather and/or equipment acting up.