Sorry, albatross.............. I live in Oregon, so can't help you on your Penn lakes question.
However, something tells me that; "trout swim about the same, no matter where you find to fish for them", (except, of course, different foods for them may enter into the equation), and I DO, do, a lot of lake fishing for trout. (to answer the first question you asked).
And, actually, what you did today, is one of the oldest and probably most "tried and true" methods for lake fishing for trout!
I use a lot of different flies, when lake fishing for trout. I use my "Toon boat" a lot, too, so I'll also "troll a fly" on occasion to try and locate where the fish might be holding and at what depth.
"Wooley Buggers" and various "leech patterns", are two that always seem to be pretty productive for me. But, don't discount fishing dries on lake waters, either!! Sitting low, in a belly boat, or, slightly higher, in a Toon boat and having a bunch of trout start rising when you're so close to to the water's surface, is pretty exciting fishing when it call comes together!!
I don't know what you're lake hatches are like, or, the insects that come off when one takes place. But, out here, an awful lot of our "stream and river insects" also inhabit our lakes too so the fly selection is nothing too technical, between to two water types.
I, think, that probably the most frustrating situation in lake fishing, is simply; "Finding out, where the little buggers are hanging out"!!
Unlike, most rivers and streams, lakes have "thermal layers"....... sort of like "building a sandwich", to use a really poor comparison! But, that's about what these "thermal layers" would look like, if you could cut a cross section out of any lake!! And, the trout, depending on type, age, ambient air temps, etc. usually will "hold" in one, possibly at times, two, of these "thermal layers".
Meaning? Meaning, simply, that you cast out your Wooley Bugger and count it down, to where you think it's at about 10 feet. Then, you do your retrieve. Nothing. Why? Why, because the fish are holding at 12 feet, or lower, OR depending on water conditions, they're holding up at 5 feet, in the water column!?!! Frustrating, to say the least, but also part of the fun and science of fishing lakes!
But, it's a lot of fun, if not challenging. Also,most lakes produce larger trout than streams do and you usually have more room for experimentation as well!
So, have fun with it!
