Starting & Stopping the AS Java

On a Java-only AS (no ABAP stack), what drives the start and stop, and how is that different from a dual-stack AS ABAP+Java?

Why does a running SAP system with a Java stack always have at least two instances, not one?

When starting an SAP system, which instance must come up first, and what property decides that ordering?

During a soft shutdown of an AS Java, what determines when each server process actually stops?

What is sapstartsrv, and how many of them are involved when you start a multi-instance SAP system?

A start command reaches only one instance's sapstartsrv. How does it end up starting every instance, in priority order?

With per-priority start timeouts, what has to happen before the next-highest priority tier of instances is started?

As of SAP NetWeaver 7.10 there are no start profiles. Where does the start information live now, and what must you do after changing it?

Under which OS user does the SAP start process run, and what are its three ordered steps?

In what order is an SAP system stopped, and which instances are always stopped last?

When you stop the SAP system, on which platform does the database go down with it, and where must you stop the DB separately?

True or false: when starting a Java system, the database must already be running before the Central Services instance can start.

In the start sequence, where must the database be operational relative to the Central Services and application-server instances?

A user triggers a soft shutdown of a running Java instance. Can users already logged on still have their requests served, and what changes immediately?

After a dual-stack AS ABAP+Java instance has started, can you restart just the Java stack without cycling the whole instance?