I absolutely agree. Without a constant supply of trade partners, standard cards are an easy way to lose money- I've hit that speed bump many times. I also found what you have involving binders- the less competitive the players I'm trading with, the fewer binders I want to have with me, because it will take so much longer to complete the trade.

In regard to the 1st half, I basically stay out of standard stuff unless I feel it's considerably underpriced, when I need a copy for an EDH deck or when my trading partner agrees that in time these will be crap rares and will value accordingly (I've got one guy in particular who's a good source for this). I kept losing too much on standard cards as I couldn't move them before rotation because unfortunately there aren't too many people around I could trade with.

As for the 2nd half, I could be mister suitcase, but most of the time I opt to limit myself to 3 fairly small binders. I almost never bring my truly high end binder (alpha/beta stuff, duals, forces, etc.) even though that's quite a small binder and I certainly don't bring the big binder with anything not worth adding to the 3 I usually bring. As I carry around my cards in a backpack my back also very much appreciates this. The 3 binders I bring are 1 binder with non-foil cards ranging in value from approximately $3 to $30, 1 binder with interesting stuff below that including some cheap but playable foils, uncommons and even some older commons (the first binder does have an Alpha Llanowar Elves, but otherwise hardly any commons and few uncommons) and 1 binder with some foil and non-foil cards that I have purchased or traded for with the goal of selling them. I do trade out of this 3rd binder, but it allows me to tell my trading partners that the offer should be good for me before I even consider it as these cards are supposed to bring in money.

I'm actually thinking that even with 3 binders I might be bringing too much. I could browse through them quickly, but most I trade with need to read cards and still spend considerable time. Also most I trade with don't have that many interesting older cards, which makes me run into the fecthes issue not for a particular card that I have many copies of, but for older cards in general. I might have to move to sorting cards by age instead and only bring out the older stuff if it looks like people will have something to offer for it.