there is most certainly a law for the headlights. You can call your family up and ask. Any officer can and will tell you that one right off the top of their head! and yes, you are somewhat correct, they are rules pretty much as other states have.. and some others do have this headlight law..
http://archive.flsenate.gov/statutes/index.cfm?App_mode=Display_Statute&Search_String=&URL=0300-0399/0316/Sections/0316.217.html
Title XXIII
MOTOR VEHICLES
Chapter 316
STATE UNIFORM TRAFFIC CONTROL
View Entire Chapter
316.217 When lighted lamps are required.
(1) Every vehicle operated upon a highway within this state shall display lighted lamps and illuminating devices as herein respectively required for different classes of vehicles, subject to exceptions with respect to parked vehicles, under the following conditions;
(a) At any time from sunset to sunrise including the twilight hours. Twilight hours shall mean the time between sunset and full night or between full night and sunrise.
(b) During any rain, smoke, or fog.
Now if you have your wipers on, it is raining correct.. so when you have your wipers on, you are to have your headlights on.. that is the law.. if it is raining to where you are using your wipers, you must use your headlights. Rule of thumb.. wipers.. headlights.. get it now??? you even stated rain, why else would you be using your wipers on a steady basis.. it isn't meant that you turn them on when you wash your windshield??? Rain = windshield wipers. If you don't have your wipers on in the rain, they will give you a ticket, if you don't have your lights on in the rain they will give you a ticket. simple as that.... so, when you have your wipers on and no lights, that equals a ticket.. do you understand now. They don't have to say you have to use your wipers, most people understand that when it is raining, you use your wipers..
I suggest you talk to your Officer (cop) family member about the rules of the roads here in FL. I admit, I don't know the rules of the road where you live, but I do where I live...

and I know I can legally drive in the left lane on the interstate with the flow of traffic and I must use my headlights if I am using my wipers (and I use my wipers when it rains

)
I do think the wording of the learners permit book is a bit confusing and not fully explaining laws. They are telling the learner what and what not to do, but not stating what is and what is not legal, get what I am trying to say. Sure, drive to the right as much as you can, expect for passing, but it most certainly is not illegal to drive in the left lane as long as you are going with the flow of traffic. If that were the case, they would not be able to pull you over and ticket you for going to slow in the left lane now would they? In Fl they can do that..
That handbook is a guide, it doesn't state the laws. The laws are in the Fl Statues. I have posted the link several times here. Like I said, check with your family members, or just read the Statues..