Salaries: I plan to use spotrac.com as the source for salaries. The site lists the year-by-year contracted salaries as well as arbitration status, free agency status, and options (player, club, and mutual). Prior to the start of the preseason draft, I will transcribe the data into an Excel spreadsheet (contracted salaries for each of the next 4 seasons and color-coding to indicate seasons when the player is expected to be arbitration-eligible or enter unrestricted free agency, and the various options that are part of some contracts. I would expect to have all that gathered so that all owners will have those salary-related factors readily available for each player. The beauty of Excel is that this data can be filtered, sorted, or arranged with just a few clicks. Again, assuming reasonable Excel skills.
There will be in-season supplemental drafts. Players drafted mid-season will have their salaries prorated based on games remaining in the season. If a player is dropped, there is no salary relief for that. The salaries are locked in. I have been toying with the idea of a partial salary relief for players placed on the 60-day relief (something like a 30% discount/recoup).
This is an experiment. At the end of the year, things could go any of four ways: 1) continue forward as is 2) use the 1st year as a "practice" year and start fresh in 2025 with everyone having a better understanding of the variables at play 3) if things go really well and there is a willingness, think about expanding 4) disband and go back to the drawing board. Personally, I would be approaching it as scenario #1 ... but that's me. I enjoy putting in the extra work and planning long-range.
Each season is a vacuum. In 2024, an Ohtani-owner would only be responsible for the $70 million expense for that season. However, it would make sense that the system should also ensure that no future seasons would exceed the cap - to account for escalators that would cause theoretical future issues. Since you bring up Ohtani - any owner should keep in mind that Ohtani alone would chew up 37% of the '24 cap. That's a bitter pill,for sure. Ohtani is an outlier and to tweak rules to accommodate an outlier would undermine the purpose of the cap.
I know there are owners out there who would take a view of "well if there is no Ohtani, I don't want any part of it." I don't pretend this is everyone's cup of tea. I hope we can find a group who are willing to give it a chance and see how it goes.