The great thing about ability checks is anyone can try anything. You want to know about monsters thats an Int check (possible prof bonus from skills like survival, nature, arcana, religion, etc), want to swing on a chandelier and leap onto the back of an ogre thats a Dex check (possible bonus from athletics or acrobatics), want to get the bandit chief to back down thats a Cha check (intimidate).
When you start thinking about things like, it doesn’t say Monster Lore on my character sheet so I can’t possibly know anything about monsters is when you get into the 4e mindset of, it’s my turn let me pick my power.
But if you want a mechanical monster lore ability look at the Sage background or Hermit background, the discovery could be a Monsternomicon or even a wagon of books and lore like what Nick has in the TV show Grim. You could even make your own monster specialist background and work with your DM about the exact benefits.
DMG 270 – 271 includes alternate initiative rules, which allow for rolling every round and add a speed factor for different actions that alters your initiative for that round. Spells are still instantaneous, raw, but they slow you down in the imitative order. A quick homerule could say that you start casting at your original initiative slot, and the spell resolves on the new slot, allowing people faster than the caster a chance to interrupt.
EDIT: to add more realism (at the expense of clunkier combat), the caster begins casting the spell at their original initiative slot, and takes their move and stuff then, but the spell doesn’t resolve until the modified slot.
So, as an example, Tim the Enchanter rolls a 20 initiative, putting him at the top of the order for the round. He goes first, moves, and starts casting fireball. As a third level spell this would go off at initiative slot 17. Anyone who goes between Tim and 17 has a chance to interrupt.
When you take the Cast a Spell action you begin casting a spell. The spell will not resolve / go into effect until a number of initiative slots have passed equal to the spell’s level (cantrips don’t have a level, and are uneffected). If you take damage during this time you must succeed at a concentration save (DC 10 or half the damage dealt, whichever is higher) or lose the spell.
EX: Casting a 3rd level spell, the spell will resolve 3 initiative slots after your turn.