Painting doubts: Clear coat or lacquer? White primer?

[DeusM]

Hey guys, So I'm finishing my pedal. And so far so good. I already applied the primer and the paint and its looking good. Now I'm applying the waterslide decal and once its dry I'll apply the clear coat. Now, I was watching some videos and I noticed that there IS a lacquer that is of course transparent that is from the same brand that the clear coat I have. Rust Oleum. Now, I read and read over the internet and people say that clear coat is the same as lacquer but then why are those two products from the same brand? Maybe they are from different uses. They seem to be for the same purposes though. Also, I have other doubts:

1) If the primer is already white why to pain? Is it because other reasons I guess? (Better finish, clear coat - lacquer "grabbing" better to the paint than the primer. Cant find a better word than grabbing...) Also I have a white paint that is shiny so it looks better but I want the technical reasons, so I'm sure I'm not wasting paint

2) How much time should I let the decal dry? Is a couple of hours ok to apply the clear coat? (I let the paint dry for 24 hs.

3) Clear coat - lacquer. Are they the same? Are they not?

I want to say that this is the last part of a project I started like a year ago and that maybe of you guys know about this since I posted more that 10 questions about different things  . But I couldn done it without the help from you guys so thank you! I'll be posting some images soon about the project and about different thinsg that I went through.

Update: Tips for cleaning the enclosure before clear coating?
This are the paint I use. I noticed some people say "use primer that is for metals" This doesn't say it's specifically form metal, It says metal, wood, plastic, etc. I didn't had any problems though.




I'm not sure the last one is a clear coat. Maybe it's just transparent paint but in the can it's says is for protecting the surfaces.