Astralaga should be allowed to join another club with "buyback + 50%" type of deal. At 21 I would prefer he goes to another club that is willing to invest in him. He isn't really a prospect now.
Kochen and Yaakob should be moved on loans indeed. Not necessarily in Spain btw, just find a club willing to play them as a starter. Belgium, Portugal, Netherlands etc could all be good options for them. I prefer the idea of signing some cheap ancient veteran as 3rd GK.
In reality, I expect Astralaga to stay with first team, Kochen becomes Barca B starting GK another year, and Yaakob getting loaned, only because his agent is forcing the decision on us.