Moving a site in early development from CSS/HTM to PHP

Question

Hello.  I am early in the development of my latest site, which I began constructing using CSS and HTML.  My pages were .htm's.  After studying up on .php, I decided that i wanted this site to be in .php, so that I could do some things server side, like having secure forms for contact and etc..
So I made a new index page in .php.  I copied and pasted the code from my index.htm into the index.php, and attached the CSS style sheets that I had created.  So everything is displaying correctly in the new index.php, as it was in the index.htm.  Can someone let me know if this is an okay practice.. a legit way of going about what I'm trying to do?
My next question revolves around hyperlinks.  Is the creation of links fundamentally different in .php than in .html?  I figured you could make links in the same way, by moving to html in the properties panel and turning text on the page into a link.  However, when I go to view the page in a browser and try the link I made to another page in the site, and it asks me if I want to open up a file (note: I did not set up a local testing server).  Do you need to set up a local testing server using MAMP (i'm on a Mac) in order for links to function properly in a .php page?  Or should I be creating the links in the php code, by using the echo function?
And of course last night I was trying to set up my local testing server and was having some struggles getting it to work.  I still have to figure that out, but before I ask you how to do that, I think I will try some more resources on the web, as there seems to be some videos available on that topic.  And yes I did copy all the files of the site that I'd like to test to the root directory of htdocs in the MAMP application folder, I'm must just be getting some of the settings wrong in the manage sites dialogue box.
Any help/insight would be of a great help!  I know this is fairly simple stuff, but thanks!

Answer 1

So I made a new index page in .php.  I copied and pasted the code from my index.htm into the index.php, and attached the CSS style sheets that I had created.  So everything is displaying correctly in the new index.php, as it was in the index.htm.  Can someone let me know if this is an okay practice.. a legit way of going about what I'm trying to do?
That's fine.
Won't make any difference to the server or the end result in browsers until the server finds some PHP script in your page to process before sending the page to browsers.
A .php extension merely tells the server to check the page for PHP script to process before delivering the page to a browser. If it finds none, nothing happens server-side. The page is simply sent to the browser.
My next question revolves around hyperlinks.  Is the creation of links fundamentally different in .php than in .html?  I figured you could make links in the same way, by moving to html in the properties panel and turning text on the page into a link.  However, when I go to view the page in a browser and try the link I made to another page in the site, and it asks me if I want to open up a file (note: I did not set up a local testing server).  Do you need to set up a local testing server using MAMP (i'm on a Mac) in order for links to function properly in a .php page?  Or should I be creating the links in the php code, by using the echo function?
There's no change to your normal HTML coding practices when using PHP pages. They're regular HTML pages with PHP script sprinkled through them. The script is processed by the server. End users never see it in their browsers.
Browsers understand HTML. A link is a link. Created the same as always.
PHP scripts in the page are processed by the server, then inserted in the page then delivered to the browser.
A testing server is required if you want to test PHP pages locally.
You can test by saving your pages after each edit then upload to your PHP-enabled web host then refresh your browser. It works but it can be slow.
A testing server does the same thing locally. Much quicker.