1. We have a lot of ways to score hits despite not really having 50/50s. The main way for us to get a hit and start a combo is through establishing a neutral and punishing them for doing different things. You can catch people pressing buttons when they are negative with our 6f d1 (we can get a combo with trait), you can whiff punish people with our 8f f1, you can catch people jumping with j1. All of these are reactionary or are in anticipation (a read) of the opponent doing something, so you need to establish your neutral game depending on the matchup.
We do have some opportunities to mix, particularly in the corner and after a trait cancel. You can also do mb low lightning in place of the overhead hit of a string, its a bit gimmicky but it works. After f12xx4 grab and f3 are pretty much a 50/50, you can also just continue pressure into plus frames and try to catch them disrespecting. We have plenty of setups in the corner that allow you to mix listed above. Also remember that people will try and crouch block f1, so keep them on their toes by using b2.
2. Reactions in game take a lot more than just reacting. You need to not only react to something, but recognize what it actually is, and then proceed to act accordingly. This all comes from matchup knowledge, knowing your opponent's most used/best tools, their frame data, and how you punish or block it. So it will come as you play more, but going into practice mode and becoming familiar with other characters will help a lot.
3. This is just raw practice. You need to drill all your combos, hit confirms, etc. so that its all muscle memory and its not taking up mental bandwidth and you can actually focus on whats going on. The more you play, the more relaxed and calculated you will get, and you will mash/freak out/do stupid things less often. If you find yourself doing it, try to slow down the game and regain your composure. Instead of continuously getting hit by Deadshot's gun as you try and brute force your way in, you're better off taking a second to slow down and think while eating some chip damage.