What a read, good stuff too.
Some questions I didn't find answered or maybe missed so I am taking a stab at it.
I find there is very little difference in bc if I do or do not use meringue powder, just a bit fluffier. The old Wilton recipes didn't have it in, think it's now a marketing ploy?
Making bc roses, have a look at this lady, I now do mine like this all the time
Finding difficulty icing your cake, make sure your icing is thin consistency and you start by putting lots on and removing some while you smooth, again youtube has a few demos on that.
Too sweet icing, I always use all lemon juice instead of milk or water, I love lemon and don't like sweet, it also helps bleach some of the yellow out from the butter. I also use the Wilton recipe but substitute butter, can't stand Crisco and I know how unhealthy it is. Just remember that lemon is a bleach so will bleach out color, best for white icing only.
For my fellow Canadians, did you know that our icing sugar has cornstarch it it which affects the consistency? Walmart carries the icing sugar from the US which is 100%. On that note, I always weigh my icing sugar ,big difference between 4 cups and 1 lb, especially if not sifted. Also, our Viva towels are patterned here so I use the Melvira sponge roller method and can get my cakes almost a perfect as fondant.
All powdered sugar from the US (Wal-Mart, or otherwise) contains at least 3% cornstarch. Some marketers don't list CS in the ingredients because it is such a small percentage that I believe it's legal to ommit it from the label.
PS without cornstarch is more commonplace in the UK.
I have found a decorator who imports non-CS PS and it costs $3.50/lb., before shipping. I would only use something that expensive for competition stringwork RI.
BTW the old Wilton Decorator Icing called for the addition of 1 egg white, that was changed after we all started to fear using uncooked egg products.
All PS in the US has some corn starch in it. Thanks so much for the info that PS from the UK does not. I have a friend that has a corn allergy and is so limited in the cakes she can eat. this might be helpful.