Update: There was no evidence of leaking in the wheel well. The oil filler gasket "looked" intact and evidently no leaks from there now. I couldn't see evidence of leaking from the spoiler but didn't take it off.
I did remove the drain plugs from the wheel well, but didn't put the CVP in a bag because car is under warranty and I don't want dealer to have any excuses. It just poured rain 2 days in a row here in Sacramento, so I will be monitoring for any signs of leaking.
Update on dealer: they are coming through. They are replacing the sticky ignition at no cost to me. I was planning to do the fix myself, but it is so convenient to have it done, now, and I can fix it when the problem surfaces again. They are also replacing the back tire, which was very worn and wearing unevenly, so now we have 4 new tires. Dealer is also addressing some other issues and didn't balk, so I'm pretty happy with the service as for now. They stated that silicone around the headlight was a standard practice, and that is what they would do to address leaking or condensation issues.
Also,I have located a reputable MB mechanic in town if I need it. They did a purchase exam on the car and helped with the rear tire issue.

My XF didn't come in as good of condition as I would have preferred, but it seems to be working out and I can't help loving the car despite the superficial flaws.
Thanks for the advice here. With the MINI, I avoided the dealer at all costs. They didn't know about the car, dodged responsibility at every opportunity, and never gave a fix that didn't require a second visit (even maintenance). I learned to do everything myself, which was rewarding as well as reassuring.

I'm finding great help and a great attitude from the experts and members on this forum. This is part of my XF experience and I appreciate you.