My first problem is that I tend to let my opponent's movements dictate my own.
As an example, say I have someone rolling alot. For some reason, this entices me to start rolling alot myself, as I feel like I have to. Is this okay, or do I need to not take after my opponent?
I know exactly what you are talking about, its very common actually, rolls "feel" safe, but if the person is of moderate or higher skill they can punish it because each roll has a set distance and end lag that can't be modified. Someone who rolls too much can be set up upon. So without any video of you, all I can really say is make sure your rolls have a purpose. If they are not avoiding a real attack or confusing your opponents, then rolling is hurting your game. Record matches and evaluate yourself, that helps a bit. I would also say don't rely on rolls exclusively, add in power shields and spot dodges into your gameplay if you don't already, I have found that excessive rolling is mainly due to the lack of familiarity with other defensive options.
It can be stressful to add this into your game play online if you care about KDR (which most of us do to some degree), so either practice with your offline friends, or if need be create a throw away wii u account where you can practice new things without having to worry about kdr. Its easier to learn offline than online due to lag.
My second issue is my lack of Neutral B and Side B usage, mostly Neutral B though.
I know alot of people rave Neutral B for a variety of reasons, but I gotta be honest; I'm scared to use it. But I KNOW it's a good tool, I just can't condition myself to use it more often. But the threat of people shielding it is just too great and it causes me to just ignore the tool. Anyways to make it harder to punish?
Nado is really good against a shielding opponent, if you Dair + fast fall nado on a shielded opponent, the sheer length of time of nado plus the little hits means that you will poke them out of shield, even at full strength. If you don't fast fall on nado you will rise too high which will get you punished, so its just a matter of practicing.
Also speaking about unsafe rolling, if I am predicting my opponent is going to roll a certain direction, I jump to the spot where I think he is going to roll and throw out a nado, the fast hits usually pick them up before they can react.
If you whiff a tornado, you can move around (zig zag) to throw people off. The move autocancels at about one and a quarter full jump's height, so you can move out of it really fast, you can also land on platforms or skid off platforms to avoid a punish as well.
There's a few other things like my lack of set-ups into UAir strings, which honestly I have no excuse for. I know how to do them, I know they exist, but For Glory has conditioned me to use the easiest follow-ups rather than more effective ones due to input delay. I just need to break that habit.
For Glory can be intense (was the case when I first playing on the 3ds), and during those moments we fall back to what we are comfortable with. Again practice with offline friends, practice mode, or on a new user account if you need to, because it really is just simply doing it, making errors, and eventually getting comfortable with it. Your game won't change if you don't experiment.
edit
I don't have recording software yet, so I can't display what I am typing, but I'm sure there are online matches where you can observe some of these things.