i would lean towards option 1 for the reason revvy mentioned as well as I would want to leave that big of a beer on the yeast for longer than three weeks for the bulk cleanup the yeast will be doing
and to answer these, yes splashing is bad once fermentation has begun. generally speaking, you need to do all your aerating before pitching the yeast.
introducing oxygen later in/post fermentation leads to oxidation (aka wet cardboard beer)
i'd go a little cheaper, but that's just me
http://www.ruralking.com/rv-antifreeze-gallon-50f.html?utm_medium=google&utm_source=cse&cvsfa=1908&cvsfe=2&cvsfhu=303436373730303335
how long have you been brewing and how many batches out of curiosity?
and september in PA in what looks like your basement so probably colder temperatures than you were having this summer = less vigorous fermentation = smaller krausen. maybe?
for being such a small store, he really carries a pretty good selection and prices are close to online. I'm surprised at what he has pulled out of the back room or tucked away in some corner when I ask for something specific
since you mentioned aiming towards the mid/higher end, have you considered doing a copper or cpvc manifold rather than braid for the MLT? That way it will work for batch or fly sparging should you desire to try either in the future and building it now will save you the cost of doing the braid...
and as for the hose, you want one designed for drinking water as normal green garden hoses can impart a taste to the water.
blue or white, the easiest place to find them is the rv section at walmart or an rv dealer/parts supplier if there's one around you