2. What happens if package P (already installed on the user's
system)
starts recommending package Q (not installed on the user's system)? Will Q
get auto-installed together with P's update, or not? I believe it's
important to keep auto-installation enabled for *new* weak relationships.
New weak dependencies of package P are installed.
Installed P-1-1.noarch (no recommends)
Available P-1-2.noarch (recommends ddd) will install ddd on upgrade if possible.
3. Similarly to above (perhaps exactly the same case), what happens
when
package Q (not installed) starts supplementing package P (installed), will
it get auto-installed or not?
No, Q will be not installed. With supplements it is difficult to known when it appears,
because that information is not on RPMDB.