You should be there during the heart of HalloweenTime, which is a lot of fun. Last year, they had decorations in both parks; the decoration in DCA were new and well worth a look. I don't know if they'll have a Mickey's Halloween Party during your stay (last year, it was the Friday before and then Halloween night), but if they have one when you're there, it'd be worth looking into.
In terms of "see it all"...I don't actually think it's possible to see everything in only two days, but you can hit most of the highlights. Being a Monday and Tuesday, it's possible that there won't be fireworks or F!, but WoC should be presented (I don't know if PtN and Pixar Play Parade will still be running or not).
I would go through a list of attractions, shows, characters, dining locations, etc. and prioritize what you want to see/do the most and go from there. DLR may only have two parks (compared to WDW's four), but there is a lot crammed into both parks.
Are you getting park hoppers? Unlike WDW, the two parks are very close to each other (about 110 yards apart - you can see DCA's ticket gate from DL's ticket gate). While park hopping does take a little time (depending on how busy the gates are), it does greatly improve your flexibility in terms of what to do and when.