Ogrork hit it squarely. Reasonable. Just last night we started a brand-new 1st-level campaign, and I pointed out to my DM, for reassurance, that I am tracking ammunition. Why? Because at 1st-level, every 1gp counts. 10 crossbow bolts is important in the grand scale of character-wealth. So's food. And buying accommodations in town. Once you hit around 4th-level and start leaving plundered non-masterwork greataxes because they're too big to drag around, it's reasonable to stop tracking 1gp level costs. The numerical importance of your food supplies becomes trivial. Its weight and size component of your Heward's Handy Haversack is likewise trivial.
Encumbrance we also mostly disregard. A character can carry the equipment he needs to be what he is. Paladins can wear full-plate and wield great-swords, even if their Str is a bit suboptimal and they shouldn't be able to without having move 5. That being said, again we're reasonable, and you're not allowed to just carry 500lb of copper coins back to town just because you whacked a bunch of giants.
We give Sorcs Eschew Materials free at 1st. Wizards have to buy a spell-component bag, but again are assumed to restock in town at statistically meaningless cost.
Why aren't there rules about equipment maintenance? Fighters should be buying whetstones and rogues should be oiling their leathers. Why aren't rangers forced to restring their bows every month? Shouldn't wizards' spellbooks get moldy if not properly preserved and maintained in a dry environment? Why do you only need to feed your horses, but never have them re-shod? Because this sort of nickel-and-dime accounting isn't any fun, at least in the long-ish term.
My personal House-Rules document includes multiclass penalties as something to be ignored. My view there is that players should be encouraged to make the character they want to make, not penalized for trying an interesting mix of abilities. If someone's willing to take a level dip in rogue to get trapfinding for the party, and it's not their favoured class by race, it's cruel to penalize them. Yes, you'll get people grabbing levels for personal benefit, but it's just not worth the accounting.