1. The playtime schedule for Supporter level access (Watcher's Pledge) as well as the other levels are kept updated on the Seasons Page here:
https://www.pantheonmmo.com/seasons/
2. Currently the D.P. is turned off. It will be turned back on next season. We don't know if it will be the same as it was or if it has been changed. The way it was previously, you keep all the gear you have equipped. You loose your money and your non-equipped inventory. You also lose some XP. If you just leveled, that could de-level you.
3. Currently characters can learn all schools of Crafting. At some point soon a big Crafting update will switch that to how it will be at release, which is explained in detail by the Crafting Dev Nephele in this post on these forums:
OF COURSE there are corpse runs to get your stuff (and some XP I think) back. I don't know how long a corpse lasts, but VR has indicated that it won't disappear quickly. Other players will also be able to drag your corpse for you.
Of course anything can change, as I said the DP might even be changed when they activate it at the start of next season.