When do I choose Upload versus Export on a Web Gallery? What do each accomplish?

Question

I am excited to be creating a Web Gallery.
1-There is not really anything that tells me when to choose upload versus export.
2-There is nothing that tells me:
          if there is a limit to the size or number of images I can put on this web gallery
          or if I need to pay for this webpage
          or how many times I can do a Web album
  Is it exporting to a file on my computer? And uploading is to a web gallery online?
3-Where do I find these answers?

Answer 1

1. Upload vs Export
Upload is used to send the gallery directly from Lightroom to you're own website. It uses Lightroom's builtin FTP client. Export creates a folder on your computer that contains all the files and HTML/Flash pages associated with the gallery. You then use your own FTP client application to upload the folder and contents to your website. In both cases it's assumed that you have a website and have access to the server.
2. You haven't mentioned which version of Lightroom you're using, but the limit to the number of photos was removed in version 5 or possibly even version 4. I have no idea what the maximum size might be., but I have a non public gallery with 700 photos and it's just under 60MB in size. Obviously, the amount of space you have access to will be determined by the web service provider or host you lease from.
3. Where do I find these answers?
A good place to start is the Lightroom Help documents (see Help menu) for Lightroom specific questions. Other questions relating to websites in general can be found using Google. This page might give you an idea as to how to create your own website How to Make / Create a Website: The Beginner's A-Z Guide to Starting a Website (thesitewizard.com)