None of us in my FS, or anyone else I ask knows what perks points are, how long it lasts, what do you get? I can't be the only one here who has no idea what these perks points actually do. I can find no decent explanation on perks either. Nor am I seeing any benefit in our points.
Have you explored the Perks tab in the Fellowship window? Most of your questions are answered in popups or hover there.
The Perks points are points the fellowship earns from fellowship-y activities, such as giving each other neighbourly help, opening tournament chests, and getting the purple fellowship bar past crystals in the Spire. The points so earned can then be 'spent', or assigned, to four different categories, each of which have distinct effects. Each level of a perk that you activate makes the next levels of all types more expensive, but the levels can be distributed into various categories as desired (i.e., you don't have to pick one category and stick with it; you could have 1 level on one perk, 3 levels on another, 7 on the third, and 4 on the last, or any various combination your group finds useful).
The Knowledge Sharing Perk gives each fellowship member 1 (or more, dependent on the Perk level) free KP point per day to use on other fellowship members' Ancient Wonders. The Tournament Archive automatically saves any points (up to a maximum, determined by the Perk level) that are over and above your last opened chest in tournament (ex: you open one chest at 7500 points, after which the fellowship as a whole contributes another 1524 points, which is not enough to open the next chest at 10000; those 1524 points are saved in the Archive, where they can then be used in a later week if you happen to be 1524 points or less away from opening another chest). Spire Archive works the same way, but with Spire points. The Advanced Help increases the amount of time that gold hands from neighbourly help stay gold (so if you usually have 24 hours to help someone back and get both the gold and supplies, the first level of this perk extends that time frame to 28 hours, and so on up the levels).
There is no time limit on these. This is a new game feature, and will continue to be around. Each Perk level that you activate will stay activated until and unless the Archmage decides to take back all of the points at once and reassign them to new categories, which might be done if it is determined that the original choices weren't as useful as expected, for example.