I mix each chanel on a mono audio file with 2 muted bars before the song intro; I place it in a folder with the name of the song with a txt file explaining bpm, sample rate, and any extra info some other engeneer will need to open it in whatever daw and mix it again if the client wants, This is the way i like when they bring me projects from other studios.
Did the same, but also stereo files where needed. Plus the Logic session, not with the bounced files, just the session I have used last for mixing. Important are information like you said. I also hate unspecific file names with no further information.
Only if client has everything-same VST/instruments/DAW-wise as my studio I can give a copy of project. Rarely the case.
Regarding storage of a completed project depends on project:
1) Hip Hop/Rehearsal recordings I would just keep multitracks on hand
2) Rock/Electronic mixes I would keep with project file
And I don't offer storing of the files to client I just giveaway them mix+multitrack. But I'll keep them for myself.
Trust is the #1 reason a client works with an AE. Distrustful behavior only undercuts the kind of ongoing relationships that we thrive on. You distrust them but they're supposed to trust you? I don't think so.
Most of my clients would have no use. But if they did, I have no problem giving them the files. They paid for them. They belong to them. I feel that I have no right to refuse.
Intellectual property rights is sort of nebulous, depending on work for hire contracts and all that. But property rights in this case are not clear because I didn't compose the content. I just captured it. Not like I'm paid for taking photos of a person, and I own the original images because they are my artistic compositions.
I run a small, project recording studio — not a data storage facility. You can rest assured that your in-progress sessions will be backed up in 4 places (2 SSD and 2 HDD via Chronosync) until 30 days after final mixes are delivered... just as you can be guaranteed that audio will be deleted after this window.
In my contract: I own the session files (and save/archive them) and the artist owns the audio. I suggest to musicians that they buy some flash drives or pay Google for storage. Easy.
If it is a mix no way..!
If it is a just a recording session, why not? Saves having to bounce stuff I guess, although in my opinion more elegant and clear to give just the files.