Personally, I don't see the point of the Beta channel for W10 with end of support nearing, and we already have a Release Preview channel to test with...
Depends what you mean by "Windows 10 Calendar". I will assume you mean the Calendar app which is being withdrawn. If so, there's no point considering...
Microsoft 365 Insider Blog:
Hi, Microsoft 365 Insiders! I’m Aaslesha Rajaram, a Product Manager on the Microsoft Designer team. I’m excited to share...