Heat is the main factor that makes a glue gun a poor choice for fresh blooms, even the low temp glue guns are hot enough to destroy cells the glue makes contact with, the resulting shrinkage keeps it from holding tight. The adhesive doesn't use heat, its similar to rubber cement, but dries much faster.
Any full service florist could order either product for you. They would most likely have to order it especially for you, if they use the product, they probably just have what they use from available, and most likely a larger container than you would want for home use. Good craft stores may carry them too, I have seen some specialty florist brands of products at Michael's. I'd bet they're available on line as well, and probably considerably cheaper- I've found floral wholesalers prices are close to craft store retail prices, by the time the florist marks them up they can be pretty pricey.
I think the stem lock would be great for designs that require a small block of oasis or with long or tall stems that need extra stability.
So true, everything cycles where fashion is concerned. That's true even with garden plants- things that were readily available 10 years ago are often hard to find currently, then you see them show up again in catalogs as "New!".
Will get some pics posted soon