With 5 plus other prioritization factors, time of application is a minor impact. It was before the other the three additional factors were added

You choose both upgrade options. Premium Plus seats will be available immediately, but you will be deducted 40 PPs even though you will still wait list for Polaris.
What is the alternative if you do not trust UA technology? You can check PZ space multiple times per day and may still miss the upgrade. Of course, when you see PZ1 or PZ2, you can decide to split the reservations into two and get the available seats if you decide not to wait list for Polaris. If you decide on this approach, you will need 50 PPs, instead of 40 PPs for each passenger if Polaris upgrade is cleared.
BTW, I saw some PZ/PN spaces for flights to TOK from hubs other than SFO for next April. I did not check other months.

copy that. I guess I was wondering if there was any particular glitch choosing that option using PP upgrades. I guess I’ll find out

While I haven't tried it myself, I've seen plenty of upgrade lists that can only be explained by people upgrading from Y to PE and then to J.

If traveling LAX ORD LHR, with the LAX ORD departing on 31Jan23 and the connecting ORD LHR departing on 1Feb23, and assuming both segments are available at time of purchase, can PlusPoints expiring 31Jan23 be used for the entire journey? What if only the LAX ORD flight is confirmed in advance, and the ORD LHR is a battlefield at the gate (ie, on 1Feb23)?

Not aware of any recent posted experiences but in the past GPU world, if on a single PNR, it was fine. If it allows you to apply to both after booking, you should be fine.

Do you pay the same "extra fees" when you use pluspoints like you do when you use a MUA on an international flight?

If you mean, do you have to pay the extra taxes that some jurisdictions charge business class customers? Yes.

Should have clarified. They show up as service fees when searching flights. (Roughly $550 to Europe)

MUA have co-pays which PlusPoints do not have

Both MUA and PlusPoints will have to pay premium cabin departure taxes. UK, Germany and France have some of the highest luxury taxes.

Both will show during a search

$550 sounds like a MUA co-pay for a deep discount economy fare. Much higher than the typical departure taxes.

Agreed. To Europe, there'd be no additional charge. On departures from Europe, you might have to pay as much as ~$200 extra for UK departures. The $550 definitely sounds like the MUA co-pay, which would not apply to PlusPoints redemptions.

Got it, thank you!

Note for deep discount economy (sub-W) you will need double plus points -- 80 instead of 40

Is there a lag between applying pluspoints and having the system 'notice' the request? Obviously on the visible waitlist, the change happens immediately, but I don't know if there might be some back-end something with a lag time. I've had a couple of odd experiences recently with late application of pluspoints (<24h) in which things didn't quite happen as I'd expected.

I can go into detail of those experiences if relevant, but basically I'm wondering about a hypothetical like this:

• T-24.1h: F is 12/16, waitlist pluspoints and move from 4. on list to 1. on list
• T-24h: system does the J2 sweep; can it happen that 2. and 3. skip 1. to get the upgrade because 1. applied so late?

I sort of think yes based on my recent odd experiences, but I'm not sure if that's the right interpretation, and I wonder if others noticed anything like this.

If you are talking a few minutes, perhaps. UA may be pre-staging the J2 sweeps. but I would doubt that is more than a few minutes. There is probably limited value in waiting to the last second to apply the PlusPoints.

Because of the nature of the pmCO systems, the various process are batched vs realtime, so some time gaps is to be expect.