Most event cards' effects are instantaneous but some are delayed or have a sustained effect. Stat boosters, threat reducers, etc.

Normally I keep an event card on the board until its effect finishes, because the cards serve as reminders. However, after reading the new(ish) rule documents, I get the impression that I should be discarding effect cards as soon as they are played.

So my questions are:

1) Does the order in which player event cards are discarded ever matter?

2) Do you discard event cards immediately or let them stick around as reminders until their effects end?

http://hallofbeorn.com/LotR/Details/Norbury-Tombs-TLR

http://hallofbeorn.com/LotR/Details/The-Power-of-Angmar-TLR

http://hallofbeorn.com/LotR/Details/Sailor-of-Lune-TGH

http://hallofbeorn.com/LotR/Details/Galadhrim-Weaver-TToR

It matters occasionally what cards are in your discard pile and in what order. I discard them immediately for that reason but usually place a token as a reminder on the affected cards.

Thanks!