Yeah, I thought it was appropriate considering the fact that Doomsday is often compared to The Hulk.
I love what they did with Lionel Luthor in the show. Before Smallville, Lex's parents were just minor characters that Lex had killed for the insurance money. In the show Lionel was a much more developed and well written character. In fact they reused Lex's origin story from the comics as Lionel's backstary in the show. Which is appropriate because in a lot of ways Lionel was a precursor to the kind of man Lex would become in the future.
Yep, I got annoyed with Lana's character after a while too. And the whole "will they, won't they" thing with Clark and Lana got old after around season 5 or so. Especially since everyone knew that their relationship couldn't last because Clark was eventually going to end up with Lois anyway. I didn't absolutely hate Lana the same way some fans did, and I do like the idea of Clark Kent having a love interest before he meets Lois Lane, but like you said Lana got way too much screen time and her relationship with Clark really overstayed its welcome after a while.
Yeah, that's one of the great things about Smallville. It had a lot of fun episodes like that.