I would like to do a large piece of meat low & slow on my gas grill as
my first attempt at "real" BBQ. Could anyone that has this experience
share some advice?

I would like to cook something that is tender and falls apart (my 1
year old son can't do steak yet, of course, no molars yet). So I'm
thinking a full rack of ribs as my first attempt or some other kind of
pork? (any ideas?)

My questions a

Do i preheat the grill for the first 10 mins? If yes, at what temp?
(low? medium? high?) Or since I am doing low & slow, do i just fire
the grill up on low and put the meat on the racks?

My gas grill has 3 burners, front to back. How many do I turn off, and
what setting (low, med, high) do I set the other burners to?

Let's say I want to do a full rack of ribs, I read something about
cutting off the membrane on the back of the ribs. Do you turn the meat
on the grill at all or just let it sit for X number of hours?

Do you need to baste at all?

Paul