Sorry if this have been answered before but what is the difference between all the Japanese Core courses? (1000~6000). I am currently working on Nukemarine's Core 2000 Anki Deck but once I finish, should I step into Core 6000 and ignore the other 4 levels in between?

there are no other levels in between... only core2000 & 6000 exist. You do 6000 after you finish 2000 and work on grammar for awhile.

Edit: this is why there is no core1000 as well

..and to make it complete: there is also a core10k! すげいじゃん？

I realize there is only Core 2000 and 6000 via Anki, but the iKnow! website lists the ones I mentioned above. Is their contents already included in Nukemarine's two-part series?

If Core 10K is a superset of 2000 and 6000, shouldn't I have begun with it instead?

Core was split into Core 1k through 6k recently. It used to just be 2k and 6k.

I see, that explains everything. Thanks.

While we're on the topic of iKnow and core, is there any Anki Decks that follow the new core order on iKnow? I impulsively signed up for iKnow a month ago. While its good for initial learning, I'd prefer to use Anki for long term rentention but I dont want to manually unsuspend every card in an Anki deck as I do them on iKnow.

Im working on that as I work my way through the iknow system. As I complete a step (100 group) I try to grab all the sentences etc. to make an anki deck. I just have no idea how to grab the audio. Maybe someday Ill try to upload them. I like the new order much better.
If anyone has a better way than to copy and pasting 100x4 into a spread sheet. Im listening.

I think the sentences from the old core and new core are the same, so maybe, as you go along can create a new index list from an old core spreadsheet to index the order of the new core. At least, it would be quicker than copying each word/sentence/meaning/reading.

Maybe slightly off-topic, but since we are talking about core decks already.. I really would like to compare my core deck with the official JLPT5-2 vocabulary lists and sort things out in Excel, f.e., in order to create a deck later on in that only the vocabs from N5-N2 are included that originally weren't in core.. any ideas how that's possible?
Also, I'd like to do the same with a 2001KO deck. I'm on Win7, just to let you know.