I find this strange considering a layout is much more difficult to learn. I had trouble with learning a tuck flyaway so I can't image starting with a layout.
At my gym we would all perform our routine for our teammates. At the end of practice everyone would have to show a routine, usually beam. Sometimes we would even be given scores. This motivated me to do my best since I was performing for an audience.
I did ballet before I even started gymnastics and continued to do it for a few years. I think it definitely is helpful. Really any type of outside training is beneficial.
I have always considered gymnastics to be the hardest sport because of all the strength and coordination that is requires. Not to mention the time it requires compared to a lot of other sports.
I think it is more of a personal preference. I have used both kinds. Velcro are definitely easier to deal with and put on but buckles are much more sturdy and will probably last longer. To me, they both work just the same.
I personally find cast handstands to be helpful when learning a giant. It is not needed but it definitely helps. Also, strap bar is very helpful. That is how I learned to do giants, with a lot of practice.