How can I regularly encourage non damage dealing moves via Hack-and-Slash?
There are RULES. LAWS. Consequences. One way to do this is to have the quest-giver have non-lethal as a parameter for bonus OR completion. OR the area where they are has strict laws. OR it's a bad idea to actually kill anyone here, the evil magic feeds on death. OR the main bad guy grows stronger with every minion you kill.
First, how can I present encounters that are obviously not forced combat situations?
LAWS and rules will help take care of that, once they are established. If they know what they can and can't do in a certain area, or that there will be consequences for it, they'll...look for other solutions. The problem with carrying a hammer around all the time is that everything starts looking like a nail. In other words, if violence is how they've always solved problems, that's how they're going to think of solutions.
There are other encounters/obstacles.
1) Environment. Thinking your way around a problem.
2) Peace! Just add children. One way to signal that maybe you shouldn't be hacking and slashing--throw adorable children in amongst the armed adults. Lost kids are always fun too. MIGHT make them pause. Maybe. Depends on the ruthlessness of the players. If they don't well...hey...you know maybe they aren't the kind of players you can do this with.
3) Meeting other travellers & merchants.You might get a meal out of it and or XP.
4) Toll Bridges.
5) They want something in order to complete their quest. Someone else has it. Killing or threatening them will not get the party the object.
6) In a city this can be an event, like a festival, parade or famous person.
7) Disaster makes heroes. A flood, a fire, the aftermath of a raging beast or curse or illness, really, could be anything. Definitely not combat, definitely is something PCs can help with.
Second, failing that, how can I present combat situations where Discern Realities, Parley, and possibly even Spout Lore are important options to consider?
You gotta get creative with it. Make it relevant. For instance, Spout Lore might help a character to know that every baddie they actually kill just makes the boss at the end stronger. Parley might be used to cross a bridge to where they need to go that would otherwise be cut from the other side (Of course you have to have something or pretend to have that they might want which could not be retrieved from your corpses, in order to do that). Discern Realities might tell fighters more about a style and where a person studied, and help them come up with a combat move to counter, or it could determine where an arrow blind is.
From the website for DW:
during a fight the GM will say that the kobold mage stays at the other end of the hall. Discerning realities could reveal the reason behind that: the kobold’s motions reveal that he’s actually pulling energy from the room behind him, he can’t come any closer.
Dungeon World IS kind of geared towards hack-n-slash, so you may have to give clues to your players that things will be run a little differently. Clues like, actually saying, out loud "I give extra XP when encounters are solved without violence" or somesuch.
Or even, just make hack-and-slash more interesting!
I have a narration of failures and successes prepared per encounter, written down in advance of the game. I go beyond the boring "You hit him, it hurts. Owie. He's not happy." That's ok part of the time, but sometimes you gotta get jiggy.
"The demon lord seems to balance back on his heels, his torso bending impossibly away from you as you try to strike, and miss. No one should be able to bend that way. When he straightens, he smiles at you, a grin too wide for his face."
"The blade bites through armor and chain, a gout of red blood hitting you in the mouth. Suddenly the world seems darker, with shadows clinging to everything. You want to roll Spout Lore to see what the effects of ingesting demon blood might be?" The effect you've added might nothing more than a special, temporary effect, that has no real number crunching effect, but might scare the player, and it might give them an edge in the fight, for example, they can see the shadows, and might be able to spot things they would not ordinarily, like a certain magic being used or item.
Other things, include hazards during fights.