SEO has nothing to do with development part of your website. It's all about backlinks and promotion of your site. You can make your website completely in html/css.
If you just want a simple website with no registration no login no complicated javascripts than it is ok to have a html website. Else i would recommend you joomla as a source.
if you dont need a database or SQL then use HTML or you can try to use CMS. it's much easier and less time. it's has nothing to do with SEO
You should ask "Is it ok to make a website in php or asp rather than html?". Basic html sites are static website with no user interaction websites while php and asp used to make dynamic website. User can interact in them. It depends on you which type of website you are looking for if you want to present simply information with large text then you may use simple html for that and if you want to go for interactive website like shopping cart website, blog type of sites, social networking site etc then you may go for php or asp. I recommend php.
I think if your requirements what you wants to offer to your user or customer is going to be fulfilled only with using HTML then you need not to make your website complicated by using any other language and more over that search engine also prefers HTML web pages more.
Depend of design, crawlers can read faster plain HTML then database driven websites. If She has to create something simple, then HTML is better solution
If you want to make a website just with HTML, you will get the one with disabilities. If you want to make multifunctional site you also need to use PHP.
hey convivial, i suggest you to go for dynamic website if you have lot of pages in your website otherwise you can use HTML with one contact-Us server side scripting page. and it is never get effect on SEO rankings.. so just use whatever suit for you website.
Same here, I use PHP so I can use the include function for headers, sidebars and footers - basically using php includes gives you the opportunity to make one change to one file and it will change it on every page of the website.