30 minutes so you don't sit by computer all the time But if you want to play all the time you can use this time to do quests, or hunt mini-bosses etc.
Dynamic xp means that your xp rate decreases as you get more resets - if you play Phobos (5000 xp), then more info is here - http://forum.muxglobal.com/index.php?/topic/721-server-settings-phobos-x5000/
On 215 res you will not be full stat, you also need all 264 quests and even then you will be a couple hundred short of max. Except MG - you can get all max on MG even without full quests.
No jewels are in shops, but you can buy them in x shop for cash points, but that is quite expensive. The main jewel.. i don't know, there is really no such thing, probably bless is the most valuable.
Yes, no exe sets are in in-game shops, you need to collect them from gold mobs, or buy from other players on web market. Quest items are available in shop if you have bought VIP status (Web -> Services ->Buy VIP account for more info). Skills - some are in shops, but the most important ones are from drops. Some skills you get from doing in-game quests. The new season skills drop from Star of sacred birth, more info about drop and bosses here - http://forum.muxglobal.com/index.php?/topic/19-drop-info-bosses-events-and-other/
Quest system is easy, i think, just go to the Quest Master in Arkania, click on him and he will give you a quest - kill 5 Scorpions, etc etc. Just go kill 5 scorpions, go back to Quest Master, receive reward and take the next quest. There are 264 quests total. Info here - http://forum.muxglobal.com/index.php?/topic/32-ingame-quest-system/
Also most of your questions are probably already answered in the here - http://forum.muxglobal.com/index.php?/forum/4-information/ - in the Information sub-forum, so please use it before asking any further questions.
GL & HF.