It doesn't matter whether you vape, use a bong, or eat a brownie, it's still considered using Marijuana.
You said you only used it about 4 times, the bigger question is how long ago did you use it.
Yes you will still need to mark the box yes no matter what it was mixed with.
As far as the drug test, unless you used it recently nothing will show up on such a test, now if it was just before you were tested and you test hot, you're probably going to be DQ'd.
Nobody here can tell you what they will consider experimental, just be honest on the form because this won't be the last time you're asked the question and the most important thing is to be consistent with your answers.
My guess is that you'll be fine, that is unless the four times you tried it were very recent, then that "could" be an issue. Again, all you can do is be honest and continue through the process and see what happens.