Please note that Australia's use of proportional representation is only in senatorial and state elections. The elections that determine who gets to form a federal government (Australian House of Representatives elections) are held under the non-proportional majority-preferential system (instant-runoff voting).
I'd like the US to both abolish the electoral college and adopt a different voting system for presidential elections. Actually, I consider the voting system used for the Australian House of Representatives more suitable for presidential elections than for parliamentary elections.
The US could abolish the electoral college without replacing the first-past-the-post system (assuming by that you mean single-winner plurality voting): https://www.nationalpopularvote.com/written-explanation
I'd like the US to both abolish the electoral college and adopt a different voting system for presidential elections. Actually, I consider the voting system used for the Australian House of Representatives more suitable for presidential elections than for parliamentary elections.