Yes, yes, and yes. As far as I understand it.
Every tap into a LL resets the clock and you can grab a new LL. And if you already have one, then you have two.
But, in the end, that doesn't give you an advantage compared to someone with one LL that they use first thing in the morning. That person can theoretically grab a new LL for their next ride that's scheduled in the next 10 minutes. And then when the tap into that ride, schedule another LL to happen in the next 10 minutes and so on.
Having an extra LL can't make that go faster. You still have to spend time on the attraction and get to the next tapstile to reset the clock and get a new LL whether you have another LL (or more) banked.
And the person who started that process with just one LL at a time first thing in the morning will always be ahead (presuming LLs are immediately available all day long).
The advantage of grabbing a later-day LL and winding up with stacked LLs is either you're going to the park later, or, your grabbing a LL that will run out later in the day.