Hi Rich,
In addition to the current YEM version 2.8.1, you can also download the YEM version 2.7.0 from the Genos download page:
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https://uk.yamaha.com/en/products/musical_instruments/keyboards/arranger_workstations/genos/downloads.html#product-tabsIn principle, you can use either of these two versions with the Genos. It is important to know that V2.8.1 works slower than previous versions. In addition, OWN packs created under V2.8.x cannot be used with earlier YEM versions. Since V2.8.1 is only required for the PSR-A5000 so far, it is recommended that most Genos, PSR-SX and PSR-S users
still use YEM V2.7.0.
Regarding Styles:Styles do NOT have to be installed via the YEM, but Styles can be loaded and played directly from the USB stick. Or you can copy it to the User drive and play it from there. This is especially true for Styles that do NOT come from Expansion Packs, e.g. for styles that are available on PSR Tutorial.
Styles in installed Expansion Packs do not take up any space in the Expansion Memory, because only the Wave samples of the Expansion Voices are copied into the expansion memory during installation. All other contents of Expansion Packs (e.g. Styles, Registration Banks, Multi Pad Banks) are automatically copied to the corresponding subfolder of the "Expansion" folder in the
User drive during installation. (And the user drive is 58 GB with the Genos.)
By the way: I recommend that you first familiarize yourself with all the important functions of the Genos (using the three manuals "Owner's Manual", "Reference Manual" and "Data List"). For example, the chapter "File Management" in the owner's manual is very important.
I think it's a little early to start with the topic of "Expansion Packs" on the first day. If I were you, I would first play/listen to all the Preset Styles including their OTS (One Touch Settings) and the Preset Multi Pads. Then you could listen to the most important Preset Voices. (In addition to the Panel Voice folders, there is also the
Legacy Voice folder, which you can access by using the up arrow in the Voice Selection Display to go one folder level up and then to page 2.)
Next, you should familiarize yourself with the
Registration Memory, because considerably more parameters can be stored in Registrations than in OTS. Information on "which parameters can be saved where" can be found in the section "Parameter Chart" in the Data List.
You could "install" the Bonus Playlist (and also the "Discover Genos" Playlist) available on the Genos download page on a USB stick (just copy the relevant folder into the root directory of a USB stick). You can also load the included
Registrations directly (not only via the Playlist function), and in this way familiarize yourself with the Registration Memory.
Important: Preset content (e.g. Preset Styles, Preset Voices, Preset Multi Pads) cannot be deleted or overwritten. Changes can be saved as User Style files, User Voice files, User Multi Pad files and/or in Registrations (in the User drive or on a USB stick). So you can never accidentally delete preset content.
I wish you again a lot of fun and joy with your Genos!
P.S.
You don't have to (and can't) learn/know everything at once. I've been dealing with Yamaha keyboards since around 2010. Via PSR-9000 I came across the Tyros4 in 2012 and finally the Tyros5, which I still play today. In 2014 there were some meetings here in Germany with the Japanese Genos development team, to which I was kindly invited by Yamaha. (At that time it was not yet known that the T5 successor would be called Genos.

) Since 2017 I have now "of course" also the Genos, to whose development, as mentioned, I was allowed to contribute a little. Since 2012 I have been dealing with the technology of Yamaha Arranger Keyboards almost every day (including in the German Yamaha Forum at the time, which unfortunately closed some time ago, and of course here in the PSR Tutorial Forum). But I'm still learning something new every day ...

Best regards,
Chris