I don't how flexibe you are in the whole mileage allowance. ORD-HKG will be less miles than a connection ORD-SFO-HKG on UA.

ORD-HKG 7782 for total status miles 17509

ORD-SFO 1855
SFO-HKG 6889
Total 8744 for total status miles 19674

Regarding the upgrades, since not enough time to get the cert in the mail, yes, you are okay in UA C. And hopefully since this month is a pretty busy month for UA flyers, hopefully you are lucky and getting op-ups especially on SFO-HKG which are always full in Y and C.

The upgrades BKK-FRA on LH would be great. If you have a connection in FRA, by having arrived on LH F, you can use the F Lounge for your connection, which is a very good thing for that early 6am arrival in FRA.