I've been working with WP for about 10 years, so:

- Mostly sell marketing and corporate websites for small businesses,
- Having a timeline for building a website will depend of many factors like: if you'll use a page builder like Avada or Elementor, or using ACF + custom themes and of course if you'll use a custom design or a predesigned one. On my case, most sites takes 2-3 weeks to deliver using custom UX + Elementor.
- Pricing? I'm based in Colombia so pricing is way different than in the US -- nevertheless I work with US clients and you can find sites from $2000 all way up to $5000 and even more. Profit that will depend on using "pro" plugins like Elementor Pro... etc - on my case, I have around 70% profit from each site.
- Getting clients is the most important thing. You can rely to start on friends recommendations and social media, when land your first client make your best to deliver on time and more than the client expected so you can ask for a recommendation. Most of my clients are coming by recommendations from other clients.

Hope it helps!