MBA,
So, as far as I know, there has been no firm date for either the release of SY0-801 or the retirement of SY0-701. The suggested timeframe for the release of SY0-801 is November 2026 (see
https://www.comptia.org/en-us/resources/comptia-exam-objectives-under-development/) .
That said, when the exam objectives for any exam have been updated in the past, at most 10-15% of the topics change. When SY0-701 was released, again, in my opinion as an instructor, that was a big change. The SY0-801 exam objectives have been posted for review, and to me it doesn't look like a very great change. About your questions:
#1. No. Exam vouchers are exam-specific. If you buy an SY0-701 exam voucher, it is only good for the SY0-701 exam.
#2. What you learn studying for SY0-701 could apply to SY0-801, but I wouldn't recommend that strategy. I advise students to study for and take an exam. I recommend that your students take the SY0-701 exam.
Regards,
Brian