If you don't want to customize the map, you can use an iframe. Though Google will rank your page content higher if the map is loaded on the page and not through an iframe. Googlebot and crawler doesn't count iframe content in the same way that it counts content loaded onto a page.
So if you're trying to rank your site you'll get a slight boost from not using an iframe. And by using the API you can customize the map and add extra features. If you just want a simple solution so that you can spend your time working on other coding projects then you can use an iframe and achieve similar results.
Makes no difference. But in terms of performance it is better to implement a static image. The easiest was to do so, is to use something like this Google Static Map Maker.