I'd say stick with four subjects. As the others have said, taking a seventh subject to replace Methods would increase your aggregate negligibly. Unless you are taking Further because you're interested in it, it really isn't worth the extra workload and pressure. After all, the increased workload of five subjects instead of four might actually compromise subjects you'd like to see in your primary four.
Your Methods score will scale to around 41, meaning if you take a seventh subject and knock the Methods score out of your top six subjects, it will only add an extra 0.9 to your aggregate - assuming you receive a 50 for this subject and all of your others. If you scored a 42 for your seventh subject, knocking your 41 for Methods out of the aggregate, you'd only be looking at an aggregate 0.1 points higher. That being said, you'd still have to achieve above a 41 in at least two other subjects (that aren't English) for your Methods score to be outside your primary four (Biology's already above 41 and English has to be there regardless).
Essentially, I don't think it would be worth taking a seventh subject, given the dramatically increased work load and the limited benefit it would have on your ATAR.
Unless you took Lit 1&2, I wouldn't take Lit 3&4. Even if you have taken Lit 1&2, from what I've heard, although Literature may be more interesting than English for those looking to analyse their texts in depth, it requires far more work and devotion to achieve a decent study score. It's just too competitive. You could be sacrificing a potentially great English study score for a mediocre Lit study score. That being said, if you really like reading, writing and analysing text, and feel you could do well in it, go for Lit