CPU cache write policy - evict already dirty? + storage of memory address
I can answer your second part.  

In the book Computer Architecture: Fundamentals and Principles of Computer Design by Dumas in 2.3.4 chapter (https://books.google.ru/books?id=TZ6VDQAAQBAJ&amp;pg=PT89&amp;hl=ru&amp;source=gbs_selected_pages&amp;cad=2#v=onepage&amp;q&amp;f=false) it is explained is much details and with better graphic aids (schemes). In summary from there: tags are most significant bytes, index are middle, but that is not by chance, for e.g. direct access adjustant  memory blocks maybe loaded together w/out eviction because they differ by index, tag will be same and will allow to check for cache hit/miss.  

Also in the book it is mentioned (not seen in wiki too) ssociative type mapping is physically organized by storing tags in special type memory - content associative memory CAM, which locates not by address, but by content. You can read more on it in wiki, where there are mentions of specific semiconductor implementations: https://en.m.wikipedia.org/wiki/Content-addressable_memory. 

As for you first question, I think it maybe not perfect phrase in Wikipedia, it is written by people and that part does not have references attached to check the wording.