There are some guides that provide a lot of guidance for some of these questions. Here is one
https://docs.google.com/document/u/0/d/1EHCM-n_4vq_Hv7V1wo9QSTcRP2ba4qRqBh8fOh5PiKk/mobilebasicYes, you lose all your AP so that you can get the AP back… slightly faster. For the artifacts, insane army cache boost is the clear answer and carry over that with a leg alloy value. Guides say don’t bother getting the AV to insane and you want to pick the 25% in the first super ascend since you lose all the AP.
Clans help with idle rewards (CW idle rewards are pretty good) and some do other activities but depends on the clan and what you enjoy in the game