Does the private key in WIF format tell if the address associated is segwit?
Since the same priv key can generate both segwit and non-segwit addresses, when importing a WIF-encoded priv key, should we ask the user if it is segwit or is that information obtained from the wif-encoded key itself?
No, it does not.
Um, so, SegWit is active but when will we see evidence of it helping?
When more people start using segwit and more segwit transactions have been made.
Have any SegWit transactions gone through yet?
Yes. There were 6 segwit transactions in the first block after segwit's activation.
Will the transaction count per block start going up?
As more people begin using segwit, it will. We have also already seen at least one block larger than 1 MB.