In Final Fantasy 13. i have most of my started paradigms to full level 3, but?

i was wondering, if i leave grand Pulse and stop doing the stone mission, can i come back to it later, say after i open up levels 4 or 5 of those paradigms? or if i leave that area to move on am i stuck doing the rest of the game? its a great leveling and farming area. i almost have my Omega Weapon crafted, just need the catalyst.

if i move on in the game instead of finishing mission 38-64 can i come back?