I think you do need to play it more. The crosses are great, you just need to direct them more and get the power right. There is no triple press. Double press does it along the ground now. Maybe, the medium height cross could be put back in for double press by Konami.
The cursor is alittle too easy alright. I don't find it too easy to score from corners. I play it on superstar though, are you on regular?
The defending is a little crap in the demo, but I don't think you understand it properly either or know fully the controls. Holding X is broken in the demo. It was meant to contain or hold up play. It does fuck all now, except run very slowly and towards the player. It doesn't hold them up at all. You need really to hold R1 and X to get your player to chase down and tackle the player. You also need to time this properly. If you run in too early, the attacker will turn away from you and you will be a step behind the attacker because your running, and that means the physics for you to change direction will be slow due to momentum. I use R2 to jockey, as you are doing, to get position on the attacker and then hold R1 and X when the time is right to run in and make the tackle. Getting position with R2 and timing R1 and X to make the tackle is crucial. Defending with X really needs to be fixed.
At 75 mins, you can defend against them. Get your defending as above right first. Also, your players are probably tired at this stage so you will probably need substitutions. Low stamina really affects their abilities in this game, especially if you have been chasing everything throughout the game.
When you pause the game, there is a command list in the menu. This will show you all the defensive controls.
You sound like you have come from playing Fifa?