Beef – Best way to preserve excess tallow long-term

Regardless of type, all chocolate should be stored in a cool and low humidity (dry) place away from direct sunlight. It would be best to seal it in an air-tight container, because, as ElendiTheTall said, the cocoa butter in it will absorb flavors.

Dark chocolate will last for years. Milk and white chocolate will last for a much shorter time (a few months), because of their milk content.

Improperly stored chocolate will develop bloom, which shows as a white or grey streaking or spotting on the surface. The spotting or streaking is cocoa butter fat separating and is a sign that the chocolate's temper has been lost. This kind of chocolate is still suitable for any application where the chocolate will be fully melted (most baking). It can even be used as the base (non-seed) chocolate for tempering with the seeding method, but it should not be used for other candy making.

If you are only using it three times a month then this 25lbs bag may last a very long time indeed.

The problem is that even white rice can eventually develop off flavors when exposed to light and air. Additionally- even if pests don't have access to the rice, it is not unlikely that the rice has some eggs on it that can hatch and spoil the whole bag.

The solutions to these problems all make it difficult to use the rice in the short term. For long-term food storage dry foods are typically sealed in either #10 cans or mylar bags. An oxygen absorbing packet is also included. This will prevent spoilage and pest growth. Mylar bags are less expensive and you can open one bag at a time for short term use.

Alternatively- if you can freeze the rice to ensure there are no pests then the rice can be stored, sealed, in a cool, dry place as others have described.

Given how cheap rice is- it might be acceptable to you to just take your chances and replace it if it spoils after some months.