Hello there Bettina,
I'll answer your additional questions in the order presented to try and keep my self organized:
(1) "So all I have to do is fill out online the LLC paperwork and pay the bill and it's done?"
Yes, indeed, it's actually a rather straightforward process these days, glad to say.
(2) "what happens if I only start the company in a few months after I have my LLC? or I never use the company (which wont happen, but you know)"
This actually happens more than you might imagine. It's no big deal. There's a couple of ways a company (and I'm using that term generically here, to include corporations and LLCs) can come to an end. One way would be by filing the necessary dissolution paperwork. The other way is be default, meaning it just becomes listed as "inactive". If you do a simple search for similar sounding names (say, perhaps, "Smith, Inc." or something like that), you'll often come up with one or two active entries and a whole list of defunct ones.
(3) "what happens when the LLC name is XXXXX XXXXX inactive?"
This is somewhat touched on above, but it generally comes down to how noticeable the use of the name is XXXXX XXXXX vigilant the owner is. For example, say I formed "XYZ, LLC", didn't do much with it, but then I happen to see that you open up "XYX, LLC" across town. I would bear the burden of sending you notice that I protest and your name is XXXXX XXXXX As a practical matter, however, this happens all the time and often goes under the radar, so to speak.
(4) "The name of the company is not taken on the Ficticious names though, can i still create a ficticious name and have the LLC?"
Yes, absolutely. Many times folks will reserve a name (akin to reserving an online domain name), thinking they have great business concept, and then go no further. As long as the state government gets their fee, that's all they care about, meaning you're not required to go any further.
And...last but not least...a most Happy Easter to you and yours, as well!