If your new website is going to use a slide show on the home page, then there are a number of things you should know.
First, there's really not a limit on how many slides you can have but you do not want to overload it. These images are larger (file size larger) than most images, so for each one you add, you're adding load time to your home page. Because of this, we would suggest having something like 3-5 images.
Second, you can manage slides yourself - there's no programming involved. With that said, you'll have to make sure you add them correctly / with best practices. This means you'll have to:
Google checks how long it takes to load a page. You have to think like Google and provide your website visitors with the best experience possible. Google (and other search engines) want to give the best results possible, which means the best user experience possible.
We have a few kinds of slide shows to choose from. We will, by default, set the transition time and transition effect (slide or fade, etc.) to what we feel works best for your website. If you want changes to our default settings, please let us know.