Rex can't gain infinite clues. Either you figure he runs out when you run out of clues in your set, or each investigator makes a trade once.
And for those of you who think that verbatim reading is the only logical way to go on some cards? Most of these problem cards are those that are in the base game or older expansions. They therefore could not have been written to account for certain effects in future expansions.
Need I remind everyone of Marie Lambeau + Martial Arts? Would she really get another +2 for her Third Eye effect because she has a third hand for casting spells? What about Axe + Martial Arts? If you're using the axe one-handed without anything in your other hand, do you get the extra +3 on the axe while still getting the +2 for the open hand? Or is she actually using two hands to grip the axe even though it doesn't say that literally on the Axe card and doesn't get the M.A. +2?
Notice that the problem cards when read verbatim are the older ones. Marie Lambeau came out before Martial Arts. Axe came out way before Martial Arts. When axe was printed, it didn't matter that they worded it the way they did as opposed to: "This weapon can be used 2-handed for +3 instead of +2."
My point: Rex came out after the Dark Pharaoh, when there was never an issue when a character didn't roll. Besides, it says "before" rolling for curses, not "before and if" so of course it still applies to fresh Curses or to Rex.
Gate bursts came out after Kate. Kate should stop gate bursts, because gate bursts--like regularly opening gates and appearing monsters--are affecting Arkham across dimensions, and her Flux Stabilizer should stop that. I also believe she should still get monster encounters in Other Worlds because why would her Stabilizer stop monsters if they're already there with her?