Basically, I kept seeing the same questions over and over and decided to compile most of the answers for them, if you don't see a FSQ answered here, or some of the answers I provided were wrong, please feel free to reply/correct me. Hope this helps you even a tiny bit.
(Some Links are also provided within the answers.)
Disclaimer: Most, if not all the information are posted by other members already, this thread is more of a compilation or rather a sort of info-center for those people who does not want to search or do not know how to. Credits to the rightful owners of the threads/links.
Q1. Do we have a list/table of [insert specific form of list here]?
A1. Yes, we have a whole forum category called Wiki, where you can find most of the specific wiki pages entitled accordingly. Also, here's a link of the DQ Wikia page if you want to access it directly: Dungeon Quest Wikia
For specific tables, here are the most useful ones: (For those too lazy to hit search)
Affixes - Contains all (I think) Affixes and their effects.
Mythics - Contains Mythic Affixes Descriptions and Mythstone Recipes.
Equipment - Contains Equipment Type List and a Jasper Conversion Table near the end.
Crystals - Contains Crystals and their Effects.
Pets - Contains Pet Types and a List of Legendary Pets.
Q2. I lost an Item/ Level/ Hireling/ Chests! What do I do?
A2. Well, you can read this post right here: Account Issues
Or if you're too lazy to click that and read another page, simply email the issue to firstname.lastname@example.org with your account email and details on what you lost. Then just wait for their reply. Good luck.
Q3. Do we have guides for Campaign(PvE) / Arena (PvPai) or both?
A3. I'm not sure if these are the exact builds that you want, but we do have a Build Compilation consisting of quite a few guides. If you didn't see it in this category, it can be located here: DQ Build Compendium
If the specific build you want isn't there, it's probable that we don't have one yet, or the guide to it is outdated. Feel free to share your own guides!
Q4. I always get Failed Match ID in arena and/or my League jumps randomly! What do I do?
A4. First of all, check if you have the latest DQ version, right now it's 126.96.36.199, if not you should update it. If you do have the latest version though, maybe it's just about your connection, but sometimes Arena does bug out. What I do when this happens, I stop playing arena for a few hours, restart DQ and/or Wifi/Data and try again, your league will return to normal after a few matches, so don't worry too much. If the problem won't go away after a day, contact support: email@example.com
Q5. I think I fought a cheater, how do I know for sure? Where can I report them?
A5. Well, you can report them here, and it also contains the guidelines to know for sure if they are hacking: Report Cheaters and Hackers
Also, there's a popular discussion thread right here, if you're interested: Cheater/Hacker Discussion
Q6. Can we have a trading/ auction function?
A6. No. Well, at least not at the moment. Currently DQ has a problem with hackers and cheaters who can edit items, it would be bad if these illegal items would be distributed through a trading system. And besides, DQ is more of an offline game, so just enjoy the thrill of farming for your own builds!
Well, that's it for now! I'll add some more if I find some more FSQs around the forums, oh and feel free to add some questions and answers in the replies. Let's help out newcomers together!