1) Do they ever explain why Helen Cutter appears to be able to detect anomalies without the aid of detection devices? She even appears to know where they lead.
2) Do they ever explain why Helen Cutter appears to not remember Claudia Brown, even though she experienced the same past as Nick Cutter and so should logically remember her?

It's been a while so I'm fuzzy...1) I think they've only hinted as to why she can do what she does and it basically boils down to she's been to the future and has advanced tech that can detect and map them. In series one she seems to do it without any aid but they imply that she does use something to detect them and that's how they came up with the radio frequency detection thing they use. In two and three they show her having devices.

2) no. Nick seems to be the only one that remembers her although she was mentioned in Eve's diary. No logic applied here.