Ok , tried to search for it but the results kinda swamped me.

First off : I have NO experience with any kind of coding/scripting whatsoever.

With that statement in mind , please be so kind to answer the following question:
Can I build a webpage solely with PHP , or do I still need to learn HTML first?

Not that I mind learning additional scripting-languages , but it would speed up my productivity , if I could get my stuff done with one tool straight off the bat.

If what I hope is true : Does PHP have noticable plusses/cons compared to HTML?

Look first thing is that, The Web browser only knows HTML, so a web page must be madeup of HTML TAGS. Yes there are many more tools to make HTML like FrontPage, DreamWiewer or many more, but when you drag a button on your page in FrontPage, It also do the same stuff (i.e It will write the HTML code to create the button itself). I didn't use PHP so i don't know that you can use HTML codes inside it or not, But if there is an option that you can do the stuff like html in php even then you have to write exactly same tags in php also.
But this doesn't mean that you can't make the HTML page without learning HTML TAGS so simple is that you can use any thing like FrontPage, or any of HTML designer which will give you a simple way to create page generate the HTML code itself, then you can simply embedd your PHP code with it.

Err.....
No Microsoft-products on my machines , so those are "out of the question"
I didn't ask for WYSIWYG-stuff ; What I asked for was whether I could do the job with one single scripting-language.
I have no qualms about "getting my hands dirty" so to say.

I'll elaborate a little more:
I figured , from what I have read so far , that PHP does provide more functionality than HTML/XHTML and I was wondering , if I could suffice with just PHP-scripting.

PHP allows you to print static HTML as well as dynamically create it, eg from form details or database results. It still ends up generating a page of pure HTML which is sent to the client. You still need to know HTML and be decent at it to be able to use the dynamic nature of the PHP generated parts of your page.

OK , that settles it then : Gonna pick up (X)HTML-skills first.
*pouts*

Dont worry, HTML is very easy once you get past the basics, and messing with Javascript (client side programming) might help you before you try PHP (server side programming). Dont forget about CSS!

This site might prove useful as it has lots of info about what you are after.

http://www.w3schools.com/