Searing blaze by far in my opinion. The creature doesnt have to die for that player damage. With the speed of rdw you are probably going to get a land drop every turn until you fizzle out (in this case you are probably going to lose anyway) or just win the game. Plus with a deck like this, 2 mana really has to be used to its most potential. 3 to creature and 3 to player is pretty decent.
I've not seen any coverage on Lucky Clover inside of burn! In mono, I found stacking browbeat turn three on a clover, I almost always get 3 cards and 5 damage off, securing turn 4 win out of those 3 cards. I swapped to boros burn, and its benefits to throwing in some pizza lands for boros charm and lightning helix is very rewarding.
If you've got some Grafdigger's Cage's in your board, there's a good chance you can outspeed Lurrus Burn. Another bonus to playing mono-red is not taking damage off your lands. So I'm gonna have to disagree with you on that one.