Aussie - I think you've based too much of your statements on this past season.
When Andrew Bogut was at the AIS, they actually won the SEABL title one year.
Note: a few years ago they didn't play in SEABL. Instead they went on overseas tours. I think they only started playing SEABL again in 2014.
I'll try and answer most of your questions:
These kids mature quickly and for most of them they are there for 2 years. So their first year is a learning experience and yes they lose mostly. You generally find in the next year, so 2017 for this crop, they will win more games.
Win/loss 2014 2/14, 2015 7/7, 2016 1/15
When SEABL finishes they have in the past played some practice/scratch matches against some of the NBL teams. They have FIBA Oceania qualifying tournament for either the U17 or U19 Worlds, depending on which year. This year there will be a FIBA Oceania qualifying tournament for the FIBA U19 Worlds for 2017.
There's also other tours - Pre-Worlds over seas tours, Adidas Nations, Nike Asia Camps, etc.
Biggest problem with these tours is they miss so much school.
Consists of individual Sessions (Shooting, Post, Ball Handling - depending on your position) or group sessions, Strength & conditioning, Scrimmages.
You must understand that these are some of the best kids in the country, so the quality of the sessions is very high.
Also, they have a gym, basketball courts, weights, plunge pool, Doctors, Physios, coaches, strength & conditioning coaches, etc all within about 5 minutes walk.
I'm not saying it is the best situation, but it is pretty damn good. However, you have to be a driven kid to go and living away from home is not for all of these kids and it helps if they are motivated, diligent and responsible with their studies.
However, most of the recent ones seem to go to College in the US, so this prepares them to live away from home and forces them to mature (emotionally) very quickly.
The occasional NBL coach visits. College coaches or assistant coaches visit, mainly trying to recruit some of the kids. There was a recent 'Try out' were a number of NCAA Colleges were present watching about 20 Aussie kids at the COE train/practice and scrimmage, not just the COE scholarship holders.