Hi Clackers...

I have some quick answers and comments for you.

EBC Number - Remember that if you see malt color expressed in Lovibond / SRM instead, the number is half. So a malt with EBC number of 4 has an SRM number of 2. (Lovibond and SRM are about the same thing, and they are half of the EBC number). If you can, look up the malter's website and get the number there. Or get another malter's numbers...which should be similar for their similar malt (like Pilsner, Vienna, Munich, etc.). And if they give a color range, I would just shoot for a number in the middle. (That is what Weyermann does, and I will give you a link to their page).

Wikipedia Page:
https://en.m.wikipedia.org/wiki/Standar ... nce_Method

Weyermann Website:
https://www.weyermann.de/eng/gelbe_seit ... &sprache=2

APA Recipe:
It goes to personal opinion but I like the BCS book APA - American Pale Ale recipe better, it is more what I would see as APA. It is a style I like and brew a lot. More late / flavor additions and more hoppy than the one you have here. BCS book is 60 minutes, 10 minutes, then 0 minutes, with 40 IBUs or so. (Your recipe was 60, 20, and 5, with IBU of 25 or so I think). If not as into hops and want to scale them back still can with the BIABacus, with more later flavor additions. And Cascade is excellent choice for APA! Most of my APAs are 100% Cascade hops. Classic hop for that style. (But I've never brewed that APA recipe you got from Aussie Homebrewer, it could be a good one...).

So you still have a tad bit of work to do with this, but this is how you do it.

Hope this helps!
Scott