1) No, Zero Suit in my opinion is not predictable compared to other characters. All of Zero's tilts have great start-up speed and recovery (except for up tilt). She can easily punish attacks off shielding (and I'm not talking about power shielding) as long as you have good recognition. I feel that her grab is what makes her unpredictable as well if you use it right. As slow as it is, some people don't expect you to use it at certain distances. This helps you set up for side B's as they might try to jump or spot dodge (thinking you will grab). Those are just a few examples... but in short, Zero has some nice mix-ups.
2) I have a few uses for the forward Smash
- My least used method of using F. Smash is for "pokers". People Like Wario who will intentionally miss you with a short hop attack, then move away from you while still in the air. Whenever the opponent is at high% (which would make this risk worth while) , I will start my F. Smash as soon as I see them jump at me and when they float backward to safety, I release. Again, this is my least used method as it's very risky in some cases. Like if you see a Wario forward Air, I'd be more likely to use this than on a Marth forward Air.
- I also use this attack for when the opponent is on the ground. Example : Trip, failed tech. I space myself so that I cannot get hit by a recovering-from-ground attack, yet I can still hit them with F. Smash if they use the attack, roll toward me, or just get up. Their only option is to roll back.... unless there's no more room on the stage for them to roll back >=) . This is a rather common use for me, though I do usually interchage this with down smash if there is no room for my opponent to roll back.
- When a player has used their 2nd jump to recover to the stage (but don't want to use up B) but must grab the ledge because they can't get far enough , I use the forward Smash a lot. *Note : Obviously, the character must be somewhat above the stage's ground level for this to work. * If you use the forward Smash in this situation, one of the two options will most likely happen. A) They get hit with the forward smash and must use up B, which equals an easy edge guard for you. B) They air dodge.... In this case... If the person is Falco, Wolf, Zelda, you basically got a free kill as they must up B upward in this situation. As for other characters, you can still try to edge guard their up B recovery. Watch your spacing though. DON'T be at the very edge of the stage charging a forward smash. There is a good chance that you will get f. Air'd by your opponent.
Hope that gave you an idea of how to use this attack.