Usually, we omit the a in a situation like this:
I'm going to eat/have breakfast.
Unless you want to say something like this:
I usually eat a [adjective] breakfast.
Or:
We're having a breakfast meeting.
Etc.
But in the specific case you asked about, eat and have are interchangeable. They both convey the same message.
According to this Ngram, have is more common, but just barely.
Note: I'm not actually American, but seeing as how there isn't much variation between American and Canadian English, I would say I can still answer this question. I also used the American English corpus for my Ngram.
Cyclist (and the almost never used cycler) refer to bicycle riders. I suppose you could apply them to uni- and tri- cycle riders, too.
I see the dictionary links show it can be applied to a motorcyclist. I rarely hear it used that way, and until I googled for an example to show you, I didn't realize it had any prevalence. From what I'm seeing, it seems to be used to mean motorcycle rider only in headlines . . .
Example of motorcycle rider and cyclist in typical (to my ear) AmE.
Contradictory evidence to my own statement, here. You'll note that the headline uses the word cyclist, but the text says motorcycle rider.
There is an American Motorcyclist Association, too. So I would throw that terminology on the pile, too.
Bike rider is generally a bicyclist. While bike can be generalized to mean any two wheeled vehicle (including motorcycles), no one would confuse the meaning as anything but bicyclist.
Biker is the only ambiguous one. While it conjures up images of sweaty, tattooed men with beards dressed in denim and leather, it can also be applied to bicyclists (although cyclist is more common than biker for this).
Typically when referring to motorcycle riders as bikers you are referring to people who live the lifestyle. To risk stereotyping: they dress the part, get tattoos, and are often members of an MC (motorcycle club). You don't usually refer to a casual motorcycle rider or someone who commutes by motorcycle as a biker.
That said, not every "biker" is a member of a gang, deals methamphetamine, kidnaps women to sell into white slavery, etc. Many are just people who enjoy the outdoor, open road lifestyle. And, many are "weekend bikers," who have run-of-the-mill weekday jobs, but, spend their weekends cruising on the roads with an MC of like-minded people.
Best Answer
NG, as an Ame speaker who has (as a doctor) delivered ~100 babies then taken care of them as they grew up, needing to know the stages of development and milestones, and needing to discuss them with (usually mom), I think I can attest with some authority to which one is common in my part of the US.
A baby crawls before it cruises (walks by holding on to things) before it toddles (takes a few unsteady steps and falls - where we get our word toddler from) before it walks. (We used the Denver Development Milestones Test, or DDII, to keep track of progress.)
Having said all that, I'm aware of creeps (alone or with along/across) and do not find it odd. In general, though, things that creep along the floor are doing so stealthily (the cat crept up on/to the bird and sprang), or horrifyingly (the severed hand crept across the floor) - generally. We even have a name for this for kids: creepy-crawly. In addition, I had a toy when I was young called Creepy Crawlers, which allowed me to make/bake plastic bugs, and, as I was a good mon, my kids did as well. (To see how this worked, visit here.)
Fun question!