Fear is just your ego playing a trick on you. Your "lack of fear" could mean you don't care about your life, and IMHO I'd be scared if I didn't have even a little fear going into the trip. On christmas, I was showing a couple friends of mine DMT... I got cocky and said "Here I'll show you how its done" and BOYYYOBOYYY, I got asskicked into candyland. It was a great experience, one I'd love to go back to, but its just I didn't expect to be shown in OEVs what is normally in CEVs. Also, after my comment of how its done, the entities told me "no we'll show you", and I proceeded to stare unerringly into the wall.... anyways, I'd love to go back to that trip and look around the world... look at my friends, see what stuff looks like, because all I saw was beautiful fractals...
Fear is normal, your going into the unknown... Say your diving and you find a cave, would you have no fear going in there? Say your home alone, its a storm outside and your in a huge house, you descend into your basement to find something, and its cold and dark.... would you have no fear there either?
If you say you honestly have no fear, then good for you. If you want to load up your device and smoke it all, go ahead (I only say this because you can only get so far before you can't go any further) if you have no fear, why would you question yourself?
As for dosages, I'd have to say one big dose seems to put me into my mind. That means I close my eyes and see wonderous fractal beauties. When I take a few small doses, I seem to create these CEVs into OEVs (this only happened on Christmas, haven't done/tried it since because I don't have a good environment for that at the moment, and I'd recommend a sitter as well, so you don't pass out).
As for largest I've taken? No clue.