Zoning: In MK9, for the most part, you can dash block your way to footsie range if you're careful enough. (Save for Freddy, Kenshi, Kabal) But in Injustice, zoning demands a little more attention. Mainly because you can't block during dash. Unfortunetly, every character's zoning works a little differently and there is no universal way of dealing with each character's zoning. Batman's zoning obviously works different than Lex's. Everyone's dash and jump are different as well. Lex's dash goes further than Batman's. Wonder Woman can use her air dash to get around zoning. Lex's jump is more floaty than Batman's ect. So a lot of zoning and your options to get around it will depend on your character and familiarizing yourself with the matchup. So be prepared for games where you get blown up trying to get in. Some matchups will be a learning experience.
The general principl is after you block a projectile, you are free to get a dash or jump in between the next one, but not always the case. Mainly depending on if you are full screen or not. For example: If you are playing against Batman and he throws batarangs at you and you block them, you would think you would be able to dash in without worry. But since Batman recovered a long time ago (batarangs travel pretty slow, like a jab fireball in sf) he actually has time to shoot you with a straight grapple if you try. So full screen, you have to be a little more careful.
Unlike sf4, few projectiles in the game have pushback. (like MK9) So you can always hold your ground that you made up. The max distance characters can be apart from one another seems larger in Injustice than MK9, so you have to cover a little more ground from full screen than what we are all used to.
Bottom line is to just be patient. Like any fighting game, zoning will be the first thing people try to expoit on people. Try some things and don't get mad if it dosn't work, try something different. Lex may be one of the best zoners in the game, so he should be good practice for everyone.