I'm sure I have this wrong, but here goes:
Lowly Silver, but with Reserve card
1) Upgrades are complimentary for myself and companion *starting* at 24 hours before departure, yes?
2) I've unchecked the C+ box so only upgrades to F would be applicable? (ie: No upgrade from Main to C+ in this case, only Main to F or C+ to F?)
3) Does companion also need to uncheck said box on their Skymiles profile? (Basically we'll be booking at least C+)

Now, assuming the above is correct:
Let's say that we do NOT get upgraded at T-24. What are the odds of DL still having F seats for purchase/upgrade for money? (I don't know if DL "waits" to get $$$ vs giving away?) I'm not familiar enough with DL and their upgrade process if by basically T-24 all available seats are assigned at that point for complimentary upgrades, nor do I know how/when the purchased upgrade window closes (ie, there's seats, but you can't buy at say T-4 or something).

I'm looking at:
5/26-5/30 round trip:
ALB-DTW (C+ would be fine on this segment-so we'll probably book it?) (this is the 6:00am flight, arriving into MCO at like 11:something am)
DTW-MCO F would be strongly desired

I know it's all a crapshoot, and if you want F, buy it. Just wondering if we chance it, or just go for it (99% of the time we just buy F anyway unless it's a very short flight like 1 hour or something). Mainly due to the seat comfort and bad back/neck problems.