Others have answered #2, for #1 I'll talk about PERCEPTION only...
While SA Training doesn't add "value" to a player it definitely increases the price you can sell a player for. Same with position eligibility. Try selling a Striker with AMC eligibility - it's almost an automatic that there will be a bidding war. Certain SA Training is much more attractive than others too. Wall for defenders is much less attractive than aerial ability for example. Generally: Dribbler, Shadow Striker, One on One, One on One Stopper > Penalty Taker, Corner Taker, Penalty Stopper. It makes sense that PERCEPTION would translate this way based on how often those SA's are called upon in a game.
Same goes with wide position eligibility, i.e. for a base DL player, DL/DC is generally more attractive to buyers than DL/DML.
Spend one token to change the name, nationality and number of the player to a famous up and coming player that is universally known. That will also greatly increase the sales price without changing the "value" of the player.