I would very much recommend it. Once it's installed you just drop in the relevant code. Perfect for smaller sites. It's also got a really simple admin area which is really important for clients who aren't very tech savvy.
I think you're getting a bit confused with cms, php etc...
CMS is the method of managing everything on the site whilst php is a server side script which performs functions before a page loads. Many CMS, use php script to gather page content from the cms before loading.
I personally use both Wordpress & ModX depending on the type of project, budget etc...
I used to create all my sites from scratch - but now I use a mish mash of frameworks, purely to increase workflow and to get more done. It's just more practical. I use wordpress most of the time, because it's got an easy to use admin, it's easy to theme for - and all web designers have some knowledge of it. I've kind of created a customised framework based on twitter bootstrap and starkers wordpress theme. Planning on sharing it on github when I learn how to use it properly...
Not sure what you mean by start from scratch. My understanding when it comes to the way that I want to build a website is that I have 2 options. They are:
Find a Wordpress theme that is very similar to the layout that I require and adapt it with its existing features. That way I will not have to worry out about how it looks in different browsers or about responsiveness. Most themes have very advanced customisation and you should not have to mess about with code, css or html.
I can do a bespoke build using Dreamweaver, or notepad. I use my own css, html, j query and responsiveness and then add it to a Wordpress theme for functionality. Would that be correct?
When I say "start from scratch", I mean work with a bare-bones framework and build on it. Frameworks are basically minimal themes that are meant to be used as a basis for other designs. They are stripped back in terms of CSS, but provide a lot of functionality and "hooks" built in. You basically create a child theme that uses the framework as a starting point for functionality. All the basic elements are there, navigation, sidebar, footer, etc, you just add your own CSS/HTML/whatever on top of the framework to make it your own.
Whether you use an existing theme and customise it, or make use of a framework, you should always create a child theme and never edit the code of the parent theme. Alternatively, look at the ModX CMS as a (better) alternative to Wordpress.