What can be done to improve mobile page load performance after you optimized all the assets (css,js,images)?

It depends on how similar the businesses are. For example if you are moving from selling shoes to selling hats versus you are moving from selling shoes to creating web apps – they are very different situations. Since you said that the marketplace model is the same, then it is probable that you can reuse a lot of the code from your current website. Both React and Node.js are up to date tools for building web apps. An experienced developer should be able to do this for you.

This is a great question, and my best Googling / Amazon-searching efforts aren't turning up much. Maybe time to write that book :) After considering this one for a bit, I can also imagine why this would be a tough book to write. With browser technology iterating relatively quickly, and with new CSS features continuously developing, any resource that dives into specifics (specific browsers, specific features, specific issues, etc) would inevitably be out of date within a matter of years, if not months. This isn't to say there can't be great resources on designing across browsers, just that talking specifics can pose a unique challenge (although perhaps great incentive to release new editions of the book each year!). That said, here are some resources that I've found helpful and somewhat timeless in their advice. Some are more general in their discussion of best practices and considerations, while others are more specifically issue- or browser- related. http://www.smashingmagazine.com/2010/06/07/the-principles-of-cross-browser-css-coding/ Smashing Magazine (June 2010) - a great article that covers general approaches to creating CSS/HTML to work across browsers as best as possible - an oldie but goodie. https://www.modern.ie/en-us/category/code-with-standards Internet Explorer (November 2013) - somewhat ironically, Internet Explorer has a great article on fundamental best practices for ensuring you have to do as little browser troubleshooting as possible late in the game. http://css-tricks.com/search-results/?q=cross+browser CSS Tricks (search archive) - when I have a CSS issue I'll often turn to CSS Tricks. If you want a good overview of general cross-browser issues to watch out for, this search results page gives a good top-level perspective. Like I said, there are lots of great articles out there covering all the issues and solutions surrounding something like IE8, but they'll be somewhat irrelevant in the coming years (e.g. https://www.tinfoilsecurity.com/blog/cross-browser-development-tips-css). So no book recommendation, alas. Hopefully some of these links might be helpful. If not, I'm serious about writing that book :)

The first thing you want to do is to stay away from major JavaScript frameworks—they are a time sink that doesn't translate into much experience down the road. Invest some time into learning the basics HTML, CSS, vanilla Javascript. Start simple with these technologies and build on that stack over time. If you start making websites with Bootstrap, React or something else, you'll quickly be overwhelmed and you'll miss on essential basic understanding. The first step for you now would be go explore CodePen, make an account and use that as a playground. It greatly reduces your moving parts, as you won't have to think about setting up a development environment. As to what to build and get your hands dirty with—find simple CodePen examples that you like, copy them and play with their code. Try changing things here and there and see how this plays out.