Wizards gain rituals more easily than any other class; they start with three rituals for free, and learn two more for free at 5th, 11th, 15th, 21st, and 25th level.
Bards only gain two rituals for free at first level, but they can cast one bardic ritual at no cost every day. At higher levels, they can cast two or three free bardic rituals per day. So they pay more up front than wizards, but they can cast for free, which wizards cannot do.
Other classes with free ritual casting are all more limited in one way or the other (up front costs or casting costs) than wizards or bards. For completeness:
Artificers gain Brew Potion, Disenchant Magic Item, Enchant Magic Item, and Make Whole for free at first level. They can use Disenchant Magic Item for free as often as they like.
Psions gain two rituals at level 1; one must be either Sending or Tenser's Floating Disk. Once per day, they can cast whichever of those two they chose. This is less choice than the bard has, and they can never cast their ritual more than once per day.
Invokers are exactly like psions as far as rituals go, except that their second free ritual is Hand of Fate. They can cast Hand of Fate once per day, and never more than once per day. Druids are like invokers, but have Animal Messenger instead of Hand of Fate.
There are also various feats which reduce costs of ritual casting, but since any class can take them, I don't think they represent a difference between classes. I will note that there are a few feats which allow PCs to make magic items with levels higher than themselves, but again, these are not class specific. They are often background specific, though.
Best Answer
The hand can conceivable answer most any question that can be answered with a gesture and whose time-frame does not extend beyond the current hour.
"Should I purchase this item" is a little vague. "Direct me to the best weapon to use in my upcoming duel" would be better.
For your second question, perhaps something like
I think the DM has the onus to keep the power useful and interesting. The hand explicitly favors reward over risk, so the DM is free to use it to get y'all into interesting encounters of just the sort an adventurer should be ready for.