As it was never really explained how Scully got pregnant, perhaps Krycek wants her baby dead because it’s proof of some sort of alien experimentation? (Upon preview, I just saw your post, soulmurk.)
In next week’s episode, Mulder gives Doggett a hard shove. That might be as close to a fight as you’ll get. 
On a slightly related note, every time I see Doggett near a car or running after a car, he’s T-1000 all over again.
Don’t think so. Next week’s epi is about the (rather inevitable) Mulder-Doggett clash.
As for Krycek popping up without warning… well, that’s not really unusual, is it? Last night’s sudden appearance was pretty typical ol’ Ratboy. 
Hey Falcon, was it you who was a fan of Krycek? Or am I misremembering?
Having/making someone else do your dirtywork is more fun.
IIRC from ‘S.R. 819’, he can’t. It wouldn’t be possible, or it wouldn’t work.
They can’t do a whole season without him, IMO. Mulder is too much of the X Files to have much of a show without him. Also, if they’re preparing to end the series, they can’t end it without him (for pretty much the same reason). I also heard a long time ago that they were going to end the season without a real television finale, but have the whole thing end with another movie. And again, you can’t have much of an XF movie without Mulder. Either way you cut it, Mulder has to come back.
Next week’s epi teaser implies that Doggett might not be a good guy. Of course, nothing keeps non-good guys from killing each other anyway (as bad guys tend to dislike each other), but it’s worth considering.
Finally, yes, CG Spender is dead. His father killed him.
Oh, a question of my own: In last night’s epi, Sheila Larkin (Scully’s mother) was named in the opening credits. But I didn’t see her in the show. Was that a mistake? Or did I miss her?