I would like to anwser some questions  as follows:

Java does not really support multiple  inheritance but
Java support a new mechanism, which can solve multiple
inheritance. It is 'Interface' and 'Implementation
interfaces'. You should integrated this mechanism with
another mechanism 'Aggregation' I think you can solve
every problems multiple inheritance.

In java, you does not care memory problem, JVM will
care them but sometime you should use 'garbage
collection mechanism' in order to free unneccessary
elements when you build specific projects, such as
project that has high complex or their execution is
persistent for a long time.

When you are a guru, you show excellent architectures
and you believe that they will use all over the world
by almost organization, companies even though
programmers. For this reason I will hope make a
standard interface so that everybody will do follow it
and you will also continue develop or extend them.

Almost questtions, which were shown here I think you
will totally understand when you work with Java
language for a long time.