I recorded some songs to a tape machine and mixed it on an analog console with outboard gear and it sounds great. My plan was to bounce this mix to an Otari MTR-10 2 track machine and send that reel to a mastering engineer to master it. Now, I am probably wording all this incorrectly and getting things wrong, but I am reading all this stuff about optimal LUFS levels and "intersample peaks" and so forth and am wondering how the heck that applies to me and what I should and shouldn't do. Is this something that I need to worry about? Do the engineers at EA think about LUFS levels?Sorry if this makes zero sense.

That's not something I'd worry about in mixing. If anywhere, mastering brings that generic idea to their process already. I wouldn't second guess your mixes based on what might happen when a random streaming service gets it. In theory their algorithms are beginning compensate for horribly squashed mixes, allowing for more dynamic recordings to be heard in the same ballpark of loudness. You should record to whatever system in the best way possible exactly the way you want it to sound.