You can pickle most anything. The size of it affects how long it’ll need but that’s about it. Just give it a go. :)

From my limited experience: just try it out! It’s a relatively easy process and you can refine after the first try.

You can use any kind. The small pickling cucumbers are usually preferred because they are firmer, and doesn't really have the soft core of the larger cucumbers, so they can stay crunchy for a longer time and they don't dilute the brine as much on account of less water content. But they are all good, because it is the pickling process that counts.

You can decore the big cucumbers, so you only have the firm flesh left, if you so desire.

any will do. Given the chance I would pick the shorter stubbier ones but dont let not finding a right kind of cucumber prevent you from pickling.

I definitely recommend giving it a try! I just do the simple fridge cucumbers, which are pretty easy and always awesome. I usually use English cucumbers, which have a thin skin that is easy to bite into. Some are pretty massive but they work all the same when you slice them.