Selecting a PHP editor

I'd like to learn something about PHP.  I am a retired network administrator (I worked on small systems, not giant installations) .  I have programmed some systems using Access and SQL SERVER 2000 so I am familiar with database and table constructs (third normal form, etc).

I thought I'd learn PHP by developing a simple recipe database.  I could do it by using Access and SQL SERVER but my server is old and dying, I have SQL SERVER 2000 and that is out of date.  I don't want to buy a new server and I don't want to spend money on buying software licenses.

My understanding of PHP is very limited. My understanding is PHP is used to create web applications.  So, I would imagine when writing PHP programs, one would use HTML coding and PHP coding in the same program.

I searched for an answer before posting this question.  The responses I found were dated in the year 2001.  I'm sure things have changed since then.

Q1.)  If my understanding is wrong, please correct me.

Q2.)  What low cost (or free) editor do you find most useful when coding PHP and HTML?   Why do you like the editor you use?

Thank you