If I may offer some further comments.
I use Ersa/Aip conversion page for hw/xw calculation. A bit more precise than e6b and I think thats what they expect in results.
Really shouldn't be the case - they both do exactly the same thing and, with a bit of care, using the whizz wheel will give you fine answers.
E6b is great tool when flying (probably not anymore with ipads), but in the exam, calculator has priority.
I guess quite true about the ipads, but, again with a little bit of care in execution, the whizz wheel will give you a final answer in the same region of practical accuracy as you get with the electronic gadget.
Also when rounding, regardless of question (fuel, wind, track, w&b, pnr/etp,..), I always use two decimals in every calculation, then round the final result at the very end.
My suggestion is just run with whatever accuracy your electronic gadget has in the background. These days, that is umpteen decimals. The secret is to make use of rolling calculations and the accumulator so that you aren't playing around with writing and entering intermediate numbers.
With pnr/etp never use 2xTAS, always use GSo+GSh.
Not really the case. The approximation breaks down at high drift angles. If the wind is light and/or more or less along track, the difference is small. Having said that, I concur with B - if you have the G/S values, prefer to use them anyway.
For A, again, we can't really help you unless we can see what you are doing. Suggest you photograph some whizz wheel settings for several examples and post them - if you are having any problems, we will see them very quickly.
When it comes to the whizz wheel, it's like anything where you exercise a skill - lots of practice and you get good at it. As Charles Goren replied, years ago, when a bridge player observed that he had incredibly good luck at the table - "the more I practice, the luckier I get !". Actually, that aphorism has been ascribed to any of many celebrities but you probably get the gist of what I am suggesting ?