Configurable Product – Selling Products by Weight: Multiple Options & Accurate Stock Management

I'm fairly new to Magento – I have no idea how to achieve what I am about to propose, nor what would be the best way to go about it.

(Note: This is not a question about the Weight attribute)

My store sells a number of products that I buy in bulk and weigh out into smaller amounts for sale to retail customers. I already sell these products in smaller and larger packs – eg 25g, 50g, 100g, 250g – these are currently set up as simple products and arranged into categories by type of product.

Eg Category: Herbs/Sage contains "Sage 25g", "Sage 50g", "Sage 100g", "Sage 250g".

This is obviously terrible. Apart from populating each category with near identical products with identical images and descriptions, it also makes stock management a nightmare: to ensure I don't sell more than what I have, I have to split up a wholesale order of, say, 5kg into 4x250g,10x100g,etc,etc. This brings up the issue that it's now possible to have 250g in stock, but not 25g if all the preallocated 25g bags have been sold.

I would like to have situation where buying any one of these products takes a total stock down by an amount representative of the size of the product.

Question 1) Is it possible to use "bundled products" for this?

I imagine something like this might work. The product with the lowest weight (25g) is a simple product – when I get, for example, 1kg more of that product from a supplier, I can then set the stock of the 25g simple product to 40 (40 * 25g = 1kg = all my stock). Then I would create bundled products containing multiples of the simple products. Eg my 100g product would be a bundle of four 25g simple products. Then, when someone purchases a larger quantity, the stock of the simple product is reduced by the correct amount. (100g product = 4 * 25g simple product, buying the 100g "bundle" reduces simple product's stock by 4)

Is this how bundled products work?

Question 2) Can I group these bundled products up into a single configurable product?

Now that accurate stock management has been taken care of above, I would like to get rid of the multiple nearly-identical products by combining all the available weights into one (I assume) configurable product. This way, only a single product appears on the site, with one image, one description, one url, etc. I could then get rid of the bottom layer of my category hierarchy, so then my single "Sage" product would sit in the top-level "Herbs" category.

Question 3) Of course, being new to Magento, I have no idea what I'm talking about. Is there a better way to achieve everything talked about above?

(I don't actually sell herbs, this is just an example)