Theme hospital end

I'm afraid I can only offer the most obvious answer: don't hire them all at once. At the start you can hire some before you start building, and some at just before opening (which will help a little).

The primary benefit of not hiring all at once is that it staggers their breaks, but also has a rather large secondary benefit: Better quality staff. The staff hiring pool refreshes every so often, giving you a better selection.

Your low-quality bulk-buy method may also be why you're suffering with breaks so much; I seem to remember lower quality staff get tired more easily.

Radiators certainly do have an impact based on their position. You can check the hospital management screen to see the current temperature of the hospital, and the general map screen shows the reach of the individual radiators. Also, staff (and visitors too IIRC) will have temperature status indicators over their heads which let you know when they're either too hot or too cold. You can move the radiators around to cover the blank spots to keep everyone a decent temperature. (Also, you can increase the temperature of the radiators so that they extend over a greater reach - although this increases the running costs).

As for the bins, plants, I don't have an answer for those specifically. In all my years playing the game (it was quite a while back though) my strategy was just to have at least one plant and one bin per room and provided you have enough handymen to water the plants (and they're not blocked off by furniture) my hospitals usually had good reputations for cleanliness and good status for plants .