con't find the addy, but there is something called ah-skin-hangar (spelt hangar IIRC)
there are templates there, and i share what i have, and have borrowed. seems most other do the same, though they dont want you basically changing a marking and calling it your skin.
you can also extract the default skin in-game with a right click in the hangar. it then gives you a look at where stuff is.
as for lines and stuff, they are a personal thing. myself i took the work truekill started, then tweaked it according the to documentation i have. i then have erased pretty much everything except the default stuff (the gear, wheels, gear brackets, and guns)
i plan on making the guns over myself, and mostly everything else.
if you want my 190 d9 template it should be fully complete in about a week. when i say complete i mean all you will have to do is the camo job, weathering, and markings. all the panel lines, rivets, bolts, and general markings (like over gas cap) wil be in place.