Dreamweaver questions

I will second what said @Jon Fritz , DW wont have any real tool included to help you develop PHP application.

concerning WP there is a kind of auto complete on the main functions and signatures (not about plugin, or specific addons... and I'm not sure that it was updated since a real while... I didn't use it anymore), but nothing on Magento

Despite its misleading name, Creative Cloud is NOT cloud-based software.  It's subscription software that you download & install on your computer's operating system.

Before you download & install a free trial of DW,  make sure your computer meets the minimum CPU & GPU requirements. Most Creative Cloud apps work on:
Windows 10 versions 21H2, 21H1, 20H2, 2004, and 1909 (LTSB branches are not supported)
macOS 12 (Monterey), macOS 11 (Big Sur), macOS 10.16 or 10.15 (Catalina)
- https://helpx.adobe.com/creative-cloud/system-requirements.html

Dreamweaver is by subscription only.  Adobe doesn't sell single purchase software anymore except Elements.

Photoshop Elements or Premier Elements (approx $100, no subscription needed).
https://www.adobe.com/products/photoshop-elements.html

Creative Cloud All Apps (51 + apps & services) and Single Apps Plans
https://www.adobe.com/creativecloud/plans.html

Regarding WordPress:  There is no reason to use other software.  Your WP online dashboard is all you need to maintain your site.

If you're creating Themes for WordPress, you can use Dreamweaver or any other code editor that allows you to work directly with HTML, CSS, PHP and JavaScript code.

I hope that answers your questions. If not, post back.

It's available as both, though I doubt many people pay the $20/month for a single program sub to it. It's "minimally maintained" at this point according to Adobe.

If you know how to work with code, you can modify just about anything in DW. There's nothing built into it that will allow you to theme WordPress without coding knowledge though.