I loved it!!
40 countries... you will need 2 more. I think the obvious place is North Territory, Darwin and Ammaroo are too big and can be splitted without problems. Also, the split aspect of the whole map (as USA map) makes much easier control the attack routes... about it, and the bonuses, some little suggestions:
North Queensland is ok. Another Oceania. Maybe you could put another route, from Ammaroo to Charters Towers... Bonus 2 is ok.
New South Wales doesnt need of 4 border countries, because it has 5 countries only. Those routes between Adelaide / Melbourne and Wagga / Warwick could disappear, and the bonus should be of 2.
North Territory: you can add 2 countries, splitting Darwin and Ammaroo. Then, you could add a route between Ammaroo and Charters Towers, as I said already. That route between Alice Springs and Sundown is not necessary, connect Ayres Rock and Thomas instead. Three border countries are ok to a bonus of 3.
West Australia: this continent should be at a little lower position in the picture. It can help to hide that "spike" in Broome. You can also put a route between Burtville and Thomas. With 7 countries and 4 in the border, a bonus of 5 is fine (3 is a little bonus for a 7 countries continent).
South Australia: cancel routes between Adelaide / Melbourne and Alice Springs / Sundown. You can then add routes between Thomas and Ayres Rock, and Lake Eyre and Ammaroo. This way you increase connections between the continents without increase number of border countries (a very high number of borders can make the continent impossible to hold). After that, South Australia will have 8 countries and 4 border countries, so 5 is a good bonus.
South Queensland: without the route Wagga / Warwick, it will have 12 countries and 4 in the borders. Bonus of 7.
Great job... the art is very beautiful, also. Cant wait to play!!