acidreign asked...

"I noticed that there is a raid entrance in old world Stratholme, could there posibly be a lore reason why that's there?"

I believe that this was their original idea for how you would get into the Scourge-related raid zone that eventually became Naxxramas. Rather than the Scourge raid being a floating Citadel, you'd go deeper into the city of Stratholme and beyond it, deeper into Scourge territory. That didn't happen, and instead Naxxramas was born.

Zakarii asked...

"I was reading on Paladin history and WoWWiki has it listed that "As paladins were immune to the Plague (and indeed all diseases), many members of the order survived the initial push of the Scourge.". If this is true, how did Crusader Bridenbrad fall victim to the plague?"

We're probably seeing an evolution of the Plague in Wrath of the Lich King. The plague we're seeing in action in Northrend doesn't entirely match up with the one we saw in Warcraft III or was written in the old RPG books. Not only has the plague had to be changed a little to fit the greater story, but the Scourge certainly wouldn't be sitting still on this thing. Your secret weapon isn't so great if there's an entire group of very powerful people who are completely immune to it. You're going to try to find a workaround, and you're going to try to find it as quickly as possible.

Icecrown has made it very, very clear that they've found that workaround.

Shelagh asked...

"My question is if there is any lore behind Thaddius. When you first run in, he says "You are too late, I must obey." Too late? Were we supposed to rescue him, or prevent him from being created? I haven't found anything about him yet, although I'm guessing it is just a random quote for a boss to say."

It's a quote appropriate to Thaddius's background, but there aren't any quests or anything of the sort that would point you toward rescuing him. Just flavor text from an NPC. If you have an Alliance character, go stand in Wintergarde Keep with Commander Eligor Dawnbringer for awhile. He tells you a little about each of the bosses in Naxxramas, including Thaddius.

Thaddius is stitched together from the women and children that were otherwise useless to the Scourge. They're the weak and innocent that couldn't make decent Death Knights or even Ghouls. They were just used as meat, and their souls are trapped within WoW's Frankenstein.

That's all for today, folks! As a note to people who want to get your answers questioned, your chances go up dramatically if you can ask your question in a clear, concise way. If it takes you 200+ words to form your question, chances are very, very good that it's going to get passed over. If you can ask the same question in fewer words, do so! Pretend that I have terrible horrible ADD and you need to get your question in before some new shiny grabs my attenti