1. 4/5
2. pseudo combos like:
-jab1>jab2>jab3 obv
-jab>dtilt
-jab>smas attack
-Jab>grab
-Jab>side-b
3. Very good move to hit when close up. Jab1 should be used for most situations if you try to do a standing grab unless they just have their shield up. The vast majority of the time it will combo into a grab if you connect with it which is why it's better than just a normal standing grab and also because jab1 has such low cool down that it will be much more difficult to punish than a whiffed grab. If they spotdodge it that is also a free grab. Jab2 is fairly useless because of how much cool down it has unless you want to combo it into jab 3. Jab 3 is a bit more useful than people think just for pressuring purposes. I like to use it to see what the opponent does to punish it and if they don't DI up and hit you out of it then I'll continue to throw it in every once in a while, Olimar is a good char to use it against because it will beat out pikmin a lot of the time. It's also a great pressuring game especially on the ledge. I like to use it a lot to sandwhich characters between the jab3 and a banana if they're standing in front of one.
4. Jab1 can force a get up but only in certain circumstances. Only the back hitbox of the jab will force the get up, since this hitbox is SO small you can't hit it unless you hit while the character hits ground from the air because otherwise the character's hurtbox won't be able to reach the jab's hitbox except in the initial connection between the ground and the character. The best way to get this setup is to send the character into his edge slip animation off of a platform and hit them on their way down.