[MENTION=6902545]Trudy[/MENTION] Have fun DMing! Always great to see a player take the plunge
Some great advice already, so I'll offer my perspective... I suspect these particular players may have been "trained" by some, let's say, sub-optimal and adversarial DMing... So my advice is coming from that angle...
Relying heavily on NPCs for answers, instead of trying to find these answers themselves.
Players interrogating NPCs to the extreme is often a sign of underlying issues:
- The DM is not presenting enough truly friendly/helpful NPCs in the game.
- The DM is not being sufficiently forthcoming with clues, and needs to be more direct (and creative) in presenting info.
- And possibly the DM is not giving enough thought about the motives of his or her NPCs, and how differently folks / monsters will respond to various interrogation methods.
Now, it's
possible your players just really enjoy interrogation scenes for whatever reason. Maybe they get a kick out of making NPCs squirm and how the DM roleplays that. In that case, I would suggest doing what I did: Spend time in advance prepping a potential/likely interrogation, with different levels of information, plot twists, and complications. You can read a detailed example of my approach
over here. In other words, roll with what they want and make interrogation as big a deal as combat, exploration, or other interaction encounters.
The tendency for high-level spell unleashing is likely the result of the DM running "one-or-two-encounters-per-day." And really this makes sense if they have no incentive to be conservative/thoughtful. As DM, don't worry about it. Simply present a variety of adventuring days (some with 12 encounters, some with 1-2 encounters, some in between, some telegraphed in advance, and others surprising the socks off the players), and let the players come to their own conclusions about how/whether to conserve their spells. If they suffer, they suffer; at least it'll be a learning experience.
I will add that you want to be transparent about your approach to long rests. For example, I typically let my players know that I adhere to the 1 long rest/24 hours rule, and that they furthermore need safety & comfort to take a long rest. An inn or elven refuge would allow a long rest, hammering a dungeon door shut with goblins in the immediate vicinity would not, and camping in the wilds I often require a group check to see how much benefit of a long rest they get.
Making poor life decisions because they don't fear reprecussions.
Consider this: For many, D&D is escapism; and for some players this means getting to act out things they don't get to do in their regular responsible lives. In other words, rogue PCs are gonna pickpocket NPCs when it would be wiser not to. It's part of the joy of D&D!
It's only if this gets to chronic levels (e.g. routinely screwing with or killing town guards, going on pickpocketing rampages in every settlement, etc) that you'll want to take a closer look.
Players accustomed to adversarial or mediocre DMing quickly develop disrespect towards most NPCs –
they are there to ruin our fun, give us a quest and never be seen again, betray us, or simply be a thorn in our side...why should we care about them? If this is the case, the key is to create good foils for the PCs – NPCs with motives/agendas/personalities that will draw the players' attention, and furthermore with sufficient power to be useful allies or dangerous enemies. That's how you start to build back the players' respect in the supporting cast of non-player characters.