Shelf life of Sesame Oil

Dried herbs really do only last around six months, certainly no longer than a year. They're generally easy to get in small quantities, though.

Spices are trickier. They'll generally last rather longer, but the time will vary. If the spice is used for the colour and/or heat (e.g. turmeric, chilli) it will generally last much, much longer than one used for its smell and/or taste. Whole spices last much, much longer than pre-ground; I generally buy whole spices from asian stores, they sell them in much larger amounts for the same prices as supermarkets; and use a coffee mill to grind the right amount just before cooking (and keep a separate one for coffee!).

If kept in the dark, in a dry, clean, airtight glass container, spices and dried herbs will certainly not become health hazards, and should not pick up unpleasant tastes or odours. The strong-tasting / strong-smelling ones will, however, lose taste and smell, eventually almost completely; since that is the whole point of using them, you might as well not bother once they're off.

White sugar was commonly used as a preservative in the past, in much the same way as salt. It's wildly hygroscopic (like salt), and an excellent desiccant, so if you packed something in it, it would accelerate the drying process. This is actually the origin of fruit jam and fruit preserves, which are still common today, even after better methods of preservation are available.

Salt was more common simply because many things like eating/living in WET sugar, so you had to be careful with how much water was in the thing you were trying to preserve. But as long as the sugar was dry it's an extremely hostile environment for bacteria and little crawly things.

Kept dry, it will last forever.