I'd say the only surprise there is that you can increase the size without rebuilding the index. Thinking about it though, it makes sense. We're only affecting future values in...

And there it is. Azure Data Platform. It's really cool. I've done a quick unboxing here.

SQL Server 2019 was not the only announcement coming out today. Keep watching. Cool stuff ahead.

Nope. You can't pause Azure SQL Database. You can with the Warehouse, but not the database.

Best approach, script all the creates and then run them when you're ready...

Indexes, or queries, are not the same between the two databases, so we're comparing apples to hammers. Look at Query 5. In the old plan, it has three index seeks....

I'd love to help out, but I really don't want to dig through all 20-30 plans here. Which one am I to focus on?

First, and most important, backups and backup testing.
Create a DR plan
Test the DR plan
Monitoring for availability, performance, behavior
Statistics maintenance
Get your databases into source control
Automate...

Those should return data. If they're not, it's likely that something is up with sys.dm_os_performance_counters, not your databases or servers. Check all the possibilities Pinal Dave lists.

Again, how are you recording them?

How are you measuring the Buffer Cache Hit Ratio on a per database basis? It's a server level metric. It's also pretty useless as a metric. Same thing goes for...