Jim Peyton at PhuturePhillies reported these signings. Nothing on the milb.com pages, nothing in BA database, so I don't know positions, ages (birthdates), nationalities, physical details, etc. JIm's reports are very reliable - he gets info at the complex sometimes long before anything appears anywhere else.
As best I understand it, these guys' signing bonuses come out of the July 2018-19 pool, notwithstanding that they signed Future Services Contracts. Their seven years of servitude don't start until the 2019 season, but their Rule 5 eligibility is driven by the date they signed the contract.