As for the main four you have selected, that will set you up well for engineering in terms of preresiquites and skills. However That is a VERY difficult combo.
For English I would ask what interests you. Do you enjoy reading? How have ur essays been in previous years or are you much more of a science guy. Because eng lan is literally linguistics which is the study of language. You get down to the HOW of language instead of the WHY in a sense (Think how does my using capitals in HOW changes the sentence is english language and the reason I am using it is normal english or lit.) Talk to your teacher and look through the study designs, but also be aware that lan is alot of memorizing metalanguage and that it is easier to pick up eng lan 3/4 than normal english 3/4.
Now for your 6th. There are a few options, I would honestly reccomend accelerating buissman and then either picking up like further or something, a uni subject or a load reduction for year 12. Year 11 will be tough with those subjects but it is doable, and accelerating an easy subject like BM or even R&S could be very beneficial as year 12 will be jammed. Doing 4/5 in year 12 will be a life saver and since the 1/2's for some of those subjects don't relate TOO much to the 3/4 then you can foccus on the 3/4 more.
Whatever you choose, just make sure you are not over doing it.