Custom zooming controls - bad practice. Better to teach people fully use their computers as their minds. They don`t know about built-in zooming feature only because "we already show them easier way". The strong reason to not use custom zooming feature and static font sizes - people with bad vision will not see your buttons at all. Use relative font sizes instead - advanced users already configured their devices for the best font size for theirs eyes, but You ignore their choice!
For page width better to use same unit as for the text content - and it is em, because when You increase font size - you do not want change paragraph line size. If it happens - will be hard to find exactly place where you stop to read text.
Images should be in good quality on every device, but keep their sizes optimal for slow 3G mobile networks.
Use real sizes only for real details and only in "printing mode"! For example: You want to print visit card or client card, which was generated in html. Use relative sizes on monitor, so client can normally read this card content on their devices, but centimeters, inches or picas - when printing.
Do not forget limit relative sizes: long text line is hard to read as same as hard to read thin columns where lines goes letter by letter. Split wide text by columns and try to not split paragraphs for only to leave/move one line to next page/column.
Watching weathercast I cannot understand how really wind is strong. For example, it shows me 5-15 m/s. Hmm... Let`s see, there is a big difference between 15 and 5 - so, is it slow and sometimes goes strongly or is it strong now and sometimes goes slowly?
My solution is to show middle minumum wind strenght, average and middle maximum.
So, when I`ll see 5-6-15m/s - it means, that wind is moustly strong, than slow!