A couple of points for you to consider:
If you were, in fact, selected for DV Fiscal Year 2025 as you stated, your Priority Date will have to become current, your Adjusment of Status filed, and all approved no later than September 30, 2025, the end date of DV 2025. Therefore, your planning would seem to be unnecessary, since you would have permanent residency (assuming your DV Adjustment of Status is approved) NLT the end of September, within your authorized grace period.
If you were, instead, selected for DV 2026, your Priority Dare will not become current in September 2025. The program doesn’t begin until October 1, 2025.
Your concern listed in #3 is something I would be concerned about. By filing the request to change from one non-immigrant visa status to another non-immigrant category while you know you are definitely planning to immediately file for an Adjustment of Status to permanent residency might well cause concern to someone at USCIS reviewing your case. There is a possibility that it could be considered a “frivolous” application and quickly denied. And, perhaps even more troubling — if your applications is quickly reviewed and refused (unlikely it will be reviewed quickly, but…), you will be considered out of status from the date your H1 ended, not the date of the denial and you may not be in status from which to apply for an Adjustment of Status.
Consulting a really good immigration attorney with knowledge of changes of status and also DV timing/filing would likely be useful to you.