The first is Bethesda spacing out the spoiler. Yes, we all experience it. You will also experience the surprise of one or two Enclave troops showing up prematurely in the wasteland. They will kick your ass, so watch out. But awesome loot for an early level character if you survive.
I don't know about the second. I experience a little hiccup now and again, especially after I clear my cache. I've determined that if I or my son plays Oblivion before the FO3 disc gets put in, I must clear the cache, as it seems that Oblivion and FO3 share part of the cache, at the same time. I have what looks like a lightning storm over Megaton sometimes, flashing sky, which disappears after about two seconds. It's a rare occurence, and though it freaked me out the first time, the game seems to resolve itself quickly, and I've never crashed with this issue. PL tends to make me crash, the first time I visit, after that it's good, though sometimes a little hiccupy.
Carry on. Don't freak out when a Robobrain flys through the air and lands at your feet, and sometimes you get XP for it.