1. What are my throw followups that i should be going for on sheik?
Down Throw into Up Air or Forward Air if Sheik doesn't DI far away from you. If she does you have no really good follow-ups. At high % you can Up Throw Up Air.
This is too vague. If you want general advice then get close to Falcon safely and knock him down so you can techchase into a big combo, then edgeguard him low. Combo into down smash to set this up reliably. You get in by running under his aerials (you might have to parry depending on which ones he is using) or by making him whiff and then getting in during his lag. Or you can read his jump and come in with a Back Air. You have to have your move out before he does or your aerial will lose. If he doesn't jump then use Down Tilt or Dash Attack to catch him out of his ground movement. If he is always retreating from your moves then take space for free and he will be cornered.
But you can't really explain a matchup quickly so if you have specific questions then you will find people can give you better answers.
Also, your questions are welcome but there is a
thread for these kinds of questions where plenty of people can answer you and it won't clutter the forum with duplicate threads.