On the Reverse Flash: Ew. Of course, the Yellow costume is pretty much unfilmable, unless you're going to camp it up.
On Logic vs Realism: The issue is conservation of premise, the more out-there elements you have to introduce, the less credible your story is, the more the audience feels another out there element can spring up. This goes for your hero and villains. If the audience can't logically see how things would work in hindsight, you lose them. Yes there's room for some rule of cool, but you can't just not care about the details either.
The danger issue is kinda separate, and that just has to do with powering down Flash so that his rogues hold a believable threat against him without Flash forgetting powers and skills as he does in comics often. Also, it's inexpensive to tear up an area and do an area effect in the comics to give Flash challenge, a movie may not be able to do that every single conflict. You can power him up as he battles foes that are far superior ie speedsters, serious masterminds, mastery types ala Grodd/Abra