Yes, thats fine- nimh cells carry a fairly high peak voltage around ~1.4v per cell, so a freshly charged pack will read alot higher than its nominal rating of 8.4v (1.2v per cell), though it will drop off fairly quickly back down to nominal or there abouts, so let it cool down off the charger and use it fairly soon after to get the most benefit.
Yeah that's OK. If that is fresh off the charger then the pack may be wearing out. Nixx cells usually peak at about 1.5V. The newer, high performance cells will peak at around 1.55V+.