Hello!!
I've always been of the opinion that honesty is the best policy so I won't sugarcoat anything.
What you are trying to do is very hard. In every game engine including this one.
Quote: "1. Is it possible to make games with a storyline"
Absolutely!
However, you'll have to write a very reduced storyline that you'll be able to tell with the tools that you have. Grand conversations with fully animated characters like they are now standart even in middle market console games are nearly impossible for the lone developer.
I've seen it done with some charm and people on here and other forums being very creative about story telling mechanics. Just note that its really hard to do.
The best game storylines are simple yet steeped in a deep and complex lore. That way you can hint at a lot and rely more on visual story telling rather than character interactions.
An extremely good example of a storyline suitable for an amateur game would be the penumbra series. (Or later Amnesia)
If you wish to rely on fully voiced characters you'll have to balance it really carefully. Amateur voice acting is often closer to cringeworthy than to engaging and players tend to have a low tolerance for stiff animations and low to zero cost voicework. If you are not afraid to rely on texted dialogues (like back in the day...morrowind for example) your game will likely come across as more mature and polished.
However, its possible. The people at SureAI released several fully voiced games and they really hold up.
Just look at the tools at your disposal first and write down a storyline with them in mind.
A final tip: A short, 6 level plot about a knight rescuing a princess (for example) is 100% more likely to result in something playable than a giant visionary plot spanning the fate of entire nations.
Quote: "2. Is it possible to have game characters lip sync to audio files"
We had a feature like this in FPSCreator and I'm hoping for it to make a comeback.
Currently its not possible in-engine. You'd have to rely on external 3D software to do this. While its possible, its not very practical for newcomers. (or cheap to get the right tools...not cheap at all!)
Quote: "3. Is it possible to have them walk around like it's a busy day and they got things to do?"
Sure! Its just a string of waypoints and animations. However this too will not be easy to script depending on how complex you want it to be.
Quote: "4. Is it possible to have different levels and once something happens it will change to another level?"
Yes. This is the easiest item on the list. Note that you can save the same map under different file names and thus be able to reload it as another level with mild changes if need be.
Quote: "5. Is it hard to make models and animations? like someone at a control panel doing something and then he leaves then goes to another control panel?"
Yes. Very hard. Modeling and animating, especially humans is a craft that will take years to master. However, you can modify purchased or stock assets that usually also come with animations and so forth. Texturing and retexturing is an essential skill for every game designer. There are helpful software suites like fuse or makehuman to help you achieve this tough. Still not an easy thing to learn.
I hope this was not discouraging for you but I feel like it'd be better for you that you know what to expect before plunging in.
-Wolf