>>85343
Glad you are enjoying it!
1. The orbs (magic stones) are like materia from Final Fantasy VII. They can do things like +max HP, +physical attack, +magic attack, boost specific elemental damage, make you attack twice, find more items in chests, etc.
2. No other characters, just a quirk of the interface. You play only as the mage, Selma.
3. There are 25 floors, and at the last floor you fight the Kochobus! You can definitely open as many chests as you want. This can be a good way to accumulate elemental crystals to power your spells and get more magic stones to equip or sell. Just keep in mind that you don't get experience if you don't fight, so you might end up with lots of items but low level.
So basically, there are six things you can encounter in a path: a monster (black ghost sprite), strong enemy (horned sprite), treasure chest (wooden, fewer items, might be trapped), rare chest (metal, more items but higher chance of trap), merchant (purple hair sprite) and rare merchant (hooded sprite).
You choose left, right, or center on each floor. If you choose a chest, you don't have to open it if you're worried about a trap. Traps and some enemy attacks will increase your sensitivity gauge, which makes you more susceptible to being tickled. Rare merchants sell an expensive item that can reduce your sensitivity gauge.
All enemies have a listed elemental weakness which you can take advantage of. Some enemy attacks will damage your clothing, reducing your defense and making you more vulnerable to tickle attacks. Further attacks can strip you down to underwear, increasing the vulnerability. Regular merchants sell clothing sets which you can use to return to fully clothed state.
If non tickle attacks hit you, you lose HP. If you reach zero HP, you can spend 8 random elemental crystals to immediately return to full HP, or 3 random elemental crystals to return to full HP but lose a turn. HP can be restored with restoration medicine (first item sold by merchants) or some spells.
If a tickle attacks take effect (because the sensitivity gauge is more than a couple of ticks above zero), you will also lose some willpower. Consider this a multiplier on your damage -- 90 willpower is 90% damage, 50 willpower is 50% damage. Willpower herbs (sold by basic merchants) bring you to full willpower.
Basic merchants always sell restoration medicine, willpower herbs, clothing sets, and bombs (damage all enemies). They then also sell random assortments of spells, weapons, and magic stones. Rare merchants always sell full restoration medicine, willpower herbs, the item that reduces your sensitivity (forget the name), and very strong weapons, spells and magic stones.
You can equip new stuff in your equipment screen (third option in main menu). The middle button in the equipment screen automatically equips the "best" gear, but usually not really the best because it doesn't know how to synergize magic stones very well.
I hope this is helpful for your enjoyment of the game! Let me know if you have any other questions.