You should have appealed the appeal further rather than abandoning it and then going for a new claim. There’s no way around completing a PIP 2. However, if you complete it a second time why would you expect a different outcome? What you actually need is face to face advice and some assistance with the form filling.
None of 1 or 2 would obviously impact an application to the UT. I’m not sure what 3 means. 4 is a biggie when it comes to udebtufying errors if law. 5 is bad advice in most cases but again wouldn’t impact.
Face to face advice is what you need at this point.
Do you have a Citizen's Advice Shop near you? I've always got them to fill out my forms and they are really good.