Welcome to the West side! Hopefully here are some useful bits of advice from my past experience with tickets and DLR in general.
I would not stress. Disneyland tends to update things as and when it suits them and even events set to be released XX days in advance will not necessarily happen on the announced timeline. I don’t know if opening the ticket prices and ability to book has been following this same laid back West Coast vibe, but if it doesn’t open up by then, just some reassurances that this is common for all other aspects of DL (most especially with dining).
One important thing to note here that right now you cannot hop before 1pm so be aware that if you intend to always enter through the dedicated hotel entrance you will need to start in DCA everyday and won’t be able to access DL with the hopper until 1pm. I believe I saw in another thread from @Bubblez that her preferred way to experience the parks is entering DCA through that park entrance no matter the intended starting park and if that starting park is DL, exiting via DCA’s main entrance & entering DL and that specifically because of the no hopping before 1pm policy, that kills this plan. So don’t let that dedicated hotel entrance be the lone reason you buy hoppers.
This is a lot trickier now but I believe theoretically possible with one giant caveat. There have to be available reservations for “hopping”. One day per park and hoppers are two different availability buckets so just because you are reserved for one park one day doesn’t guarantee that they can accommodate your ticket upgrade to then hop. It seems really weird for Disney to turn down the more money you would spend to hop and then not accommodate you to be able to hop, but they have a lot of well-versed regular guests who will loophole their way into getting into a park on a day they didn’t reserve soon enough in time to get an available reservation via this mechanism. So another hurdle on hopping.
I am very firmly in the camp that DLR needs 4 days to really do it justice, 3 is doable so I say very definitely yes to 3 days. I know we have never regretted (and have never not used) the extra days we buy, ESPECIALLY if we are already in close proximity to DL. I can’t imagine being the proximity of the GCH and NOT going. Unless you really wanted a relaxed resort only day, but even then, DCA is steps away and the difference between 2 and 3 days is $75 so it depends on how much time you would need to be in the parks to justify that extra $75. And the good news on this, is that you can buy 2 days now and as long as you do it before parks close at the end of your 2nd day, you can upgrade your 2 days to either add a 3rd or if you decide to go the Magic Key route, upgrade to the pass (and as long as you don’t us a gift card is pretty straightforward in the DL app).
Which brings us to your last question:
My best advice is to look up the blockout dates that apply for the pass and if the trip you’d plan to see Nintendo will work with those blockouts and it was already highly likely that you would add on DL as a part of that trip, it’s generally cheaper to get the pass. I always like to breakdown the pass costs into the closest combination of multi-day ticket trips that would be our “break-even” point and since we started going to DLR, I’ve yet to have the pass being more expensive than breaking out the absolute minimum number of trips we’d like to take and splitting that up with tickets for trip (but ask me again with another price increase if I can still manage buying those APs for a family of 6 )
Let us know if you have any other questions as you get to planning more details!