[Wordpress or Static HTML Sites?]

If you are making a site for yourself, that's one thing -- potentially a good opportunity to learn something new or experiment. If you are making a site for others, going with something like Wordpress that will save you time, has a strong user community and should be relatively bug free might make more sense.

 

CMS is essential if you want to have a better website developed for your business and others as well.

[How to center my javascript slideshow?]

you can easily fix that in CSS