Need Help Building A Website. . .

In my opinion if you are just starting out using HTML is the best way to go (using tables), then advance using CSS until you're able to do full CSS sites (which wont happen over night).

As for the "Supposedly far superior to using tables", reminds me of the Tui ads we have here - "yeah right".
Let me first say there is nothing wrong with CSS and I even have full CSS sites (some).
There is nothing wrong with tabled sites, tables have been around for years and if you look at 90% of the web (99% of fourtune 500 sites) you will see they are still using tables. I wont get into a tables/css debate but if you are going to pay someone to make a e-com site for you, tables will be quicker, faster, and most importantly cheaper for you.
Tables: work on any browser the same (IE has it's own tag elements thou)
CSS: simple stuff works well on all browsers, layouts etc need to be 'hacked' to suit several browsers and as new browser version (like IE7) the CSS will need to be updated (hacked again) to suit as microsoft have this thing about not following web standards.
CSS and tables can offer similar appearances, Megan (part of the admin team here) has done a great job converting this forum to CSS just about making the site tableless.

Joomla is a CMS (content mangement system), is open source (free), I think their site is http://www.joomla.org/ or do a search in here for joomla and see what our members have said about it. (can also search for tables and css, several threads/debates/discussions on this)

There are indeed a lot of areas to learn in web development.

markup
style sheets
client side scripting
server script

the list is endless.

The best place to start is to indeed learn the basics of HTML first, and lay your sites out with tables, and then move onto CSS layouts etc.

You said that you would be paying someone to build the site for you? if this is the case, they should be able to meet whatever requiremnts you have so if you specifiy the site must be built with pure css, then they should be able to do it.

Carbo wrote: For example, I am told the best way to build a site is using something called CSS. Supposedly far superior to using tables. Is this an accurate statement?

Yes, absolutely. If you are hiring a professional to design a site they should be using CSS and not tables for layout. It is the most current method. Using tables is a sign of being not up-to-date on the current design techniques.

It is not true that a lot of hacks need to be made to get it to work. If a person knows what they're doing they can design something that works on all browsers without hacks. As busy mentioned, I've been working on converting this site to CSS. There are only a couple of hacks in there right now and I *think* they're forwards compatible.

Carbo wrote: How will using CSS affect the look of the site? And future upgrades, changes, maintenance, etc?

It will look more modern and up-to-date, first of all. Future upgrades will be much easier because the design will be completely separate from the content. So if you wanted to change the design, there wouldn't be a lot of time spent on the HTML code - the designer would just update the CSS file and be done with it.

Carbo wrote: Also of concern to me is Search Engine Optimization. How is this affected by the building process?

This is another benefit of using CSS for layout. CSS generally results in less code. Less code means that the SE's can concentrate on the content. The page also needs to be properly structured. If someone is using CSS for layout they probably understand this (but not necessarily). i.e. a header needs to be marked up with header tags so the SE knows that it's important.

Carbo wrote: Finally, someone I have been talking to someone who has been selling me on the advantages of something called Joomla. Anyone know anything about this? Good? Bad? Ugly?
Any advice is appreciated. Thank you.

It's a content management system. I don't know too much about it as we've decided to use drupal for our site, but I know it's considered to be one of the better ones.