Tips for a newbie build please?

Hey all, newbie here, I have been looking at everyone's build pictures on here and am extremely impressed with what you all are coming up with! Everyone's builds look like factory options! Really hoping mine turns out that well! My first plan of attack is front cabinet and counter top of some sort. at this point, I'm not really planning on going all out camper build. As much as I would like to do that, I still want this trailer to be able to be used as a utility trailer. Cabinets would be just for camping equipment storage.
My main question, from all the builds I have seen, I THINK I'm seeing 2x3 construction for the frame work? Is that right? Are you stapling these boards together, screwing, nailing??? I'm not sure if I should buy premade cabinets and make them fit, or build my own. I would think keeping light weight is the over all goal, so my thought of main structure being 2x4 would be a bit heavy. Could someone give me some building tips? Also, how are you all fastening over head cabinets in the nose? I don't have a ton of room with having a slant nose, but thought I could at least mount stereo and speakers up there so they are hanging too low. I'm not feeling any roof bracing in the vnose for some reason. Flooring, from seeing everyone's pics, I'd like to use the coin pattern flooring. ANY building tips for a new guy would be appreciated! Here are some photos of what I have to work with. It's a 7x12 6 ft interior height. Sorry for all the mud, this was first pics when I bought it and previous owner left it muddy. Thanks for any input!
Mike
My main question, from all the builds I have seen, I THINK I'm seeing 2x3 construction for the frame work? Is that right? Are you stapling these boards together, screwing, nailing??? I'm not sure if I should buy premade cabinets and make them fit, or build my own. I would think keeping light weight is the over all goal, so my thought of main structure being 2x4 would be a bit heavy. Could someone give me some building tips? Also, how are you all fastening over head cabinets in the nose? I don't have a ton of room with having a slant nose, but thought I could at least mount stereo and speakers up there so they are hanging too low. I'm not feeling any roof bracing in the vnose for some reason. Flooring, from seeing everyone's pics, I'd like to use the coin pattern flooring. ANY building tips for a new guy would be appreciated! Here are some photos of what I have to work with. It's a 7x12 6 ft interior height. Sorry for all the mud, this was first pics when I bought it and previous owner left it muddy. Thanks for any input!
Mike