Will I know when I am lucid dreaming?

This is one of my biggest concerns. When I enter a state of lucidity in a dream will I feel different? Will things be more clear (senses and thoughts for instance)? Will I realize or know things are more clear? Will I know things were more clear when I wake up?

This might be a bit hard to explain, but I'll try:
When I dream, I don't really feel the dreams are "solid". I don't seem to be able to see like I see in real life (and I do literally mean seeing with my eyes), and the images may be fuzzy. Time also moves in weird ways, sometimes it jumps for instance. At least this is how I feel when remembering dreams when I wake up. Strange thing is, I THINK while I am in a dream everything looks and feels "right". I remember some nightmares when I felt a tone of relief when I woke up, because I actually realized then that it was just a dream. This is really confusing for me to explain / completely understand, and on top of that, I don't know how other people experience dreams, so I don't even have a frame of reference.

For example: a few nights ago I had a dream. I don't remember much about it, near to the end I remember (I think) thinking "whoa, this is a dream", because of something that didn't make sense. This was actually what pushed me into this forum, and why I decided that I was going to try and harness this. Anyway, I didn't do much with it. I remember I had some characters fighting. I brought down some sort of character selection screen, selected the characters, they came to life from their boxes and started going at it. In the dream, I remember feeling like it was actually a big deal, I remember it feeling "special" in some way, but once I woke up it was like any other dream (I think).

I hope you guys understand my confusion on this, and I hope I made myself clear enough.

The main question is really, will I know if I am lucid? I am concerned that I might be able to lucid dream, but that every dream might just be a fuzzy, unorganized mess, either when I remember it, or in the actual dream, as it occures.

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Fears and nightmares

I've heard many stories of sleep paralysis, and how some people experience really messed up things while it is happening and cannot wake up from it. Now, I know sleep paralysis is not lucid dreaming, but I can't help but think of the possibility of this happening to me. How common is this kind of incident? Is it a big deal?

I have a lot of nightmares. I honestly cannot remember a single dream I had that didn't spiral into a nightmare of some sort. They all range from scary beings, to skeletons in my closet, to big fears I have (like the fear of killing someone by accident, for instance). Can this affect my lucid dreaming? Am I bound to just have bad experiences until I can zone these worries out? How can this affect me (if it can), inside a lucid dream?

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Time

Another question I have is, how long does generally a lucid dream run (in dream time)? I've heard said we dream about 30 minutes every night. I don't know if this is true or not, but the main question is: is the dream time disconnected from the real time? Can that disconnection be dramatic? Can 30 minutes of dreaming time equate to days in your dream? I am inclined to think (much to my disapointment), that no, simply because of our brain speed. On the other hand, I've heard of people who have what feels like really long dreams, and false awakenings also point to a massive disconnection between dream world time and real life time. I wanted to hear what people think about this.

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I think that is all. Thank you very much for the attention and I hope I've voiced my concerns somewhat clearly. Sorry if the writting is a mess, but I'm really not used to writting or discussing this subject.