Exactly right. Natural selection is an agency of evolution. The change in allele frequencies is evolution.
Yes. Just evolved E. coli bacteria. The species name is always lower case, to make it clear in technical articles, while the genus name is always capitalized. I know it seems inconsistent, but it works very well to avoid confusion. Evolution can happen within a species, just as it can produce new species. Most creationists, as Stuu mentioned, allow for the evolution of new species, genera and families. Apparently, some will go as far as new orders. They just don't want to call it "evolution."
Actually, they don't broadcast pollen:
Despite the colorful nature of the dandelion flower it doesn’t actually attract as many butterflies or bees as many other flowers of similar size, such as clover or henbit. One of the main reasons for this is that dandelions don’t require pollination, therefore their flowers aren’t designed to attract insects.
https://www.ezhomelife.com/dandelion-weed/
They are bisexual, having both male and female parts on each flower, and so pollinate themselves.
You aren't killing the tall ones, of course. They live for years, unless you remove the taproot or poison them with herbicide. But by removing the flowers, you do indeed change the allele frequency of the dandelions on your lawn, which as you know, is evolution.