What is the most feature rich "book recommendation" plugin?

I've been down this road before (two custom CMS platforms built over the years), and to play devil's advocate here: do you really need to build a custom CMS? What problem are you up against that aren't being solved by existing solutions? If those problems aren't fundamental, how much time and money will be saved by creating plugins for an existing CMS? I know the temptation to start from scratch, but if this is something to be used in production, the todo list is staggering: you'll need user authentication, security on the front and back end, admin interfaces, plugin infrastructure for extensibility, theming (if this will be used for multiple clients), third party integrations — and that's all before you get into really annoying and notoriously finicky shit like media uploads and i18n. If it's for learning or a hobby, go nuts, but if you're planning to use this with clients, save yourself the heartache and late nights and use something established and open source. Join the community and help fix existing solutions' shortcomings — that's a bigger overall contribution to the world. Good luck!

There is a lot of points in your question which unless someone has the exact same setup as you - I don't think you will get the answers you are looking for. I believe you should limit it by asking yourself: What is the ONE thing the MLM plugin I am looking for can do so that it achieves the maximum amount of result to my business by using it? IMHO - it would be the ability to set commissions for the products you sell and award commissions to those affiliates that actually earn you sales. All other features, while nice, are ancillary features that from the perspective of the affiliate - don't really need in order to be successful. In that regard - I would suggest https://affiliatewp.com/. When it comes to running affiliate programs on WP sites, it wins out as the best in my experience. Hope this helps! Glad to assist any further if you need help.

I think BuiltWith will do this for you. Plug in the domain and it will tell you which technologies it is built on. Most of the well-known video sites are custom jobs, but I'm sure WP could do what you want.

Checkout is a high-quality WordPress theme by Array built for marketplaces of any kind. https://arraythemes.com/themes/checkout-wordpress-theme/ Let me know if you have any questions about implementation, and I'd be happy to setup a call.

Take the # of hours it takes you to do it and charge $50/hour. That's the price. Eventually you can charge $100/hour but that will require a bigger customer. If the customer is small < $1M in gross sales per year - charge $50/hour If the customer id medium < $1-5M / sales - charge $75 Over $5M - charge $100 The challenge you'll face is clearly defining the expectations and handoff so that you're not stuck doing stuff that you can charge for and always getting interrupted from past customers.