George, how are you getting the data from the Davis to the PC? I thought you have to have WL to communicate. As to the desktop, it's actually the "console" of VWS and there are a couple of jpg's generated that are the "Broadcast" displays you can see on the desktop. All that you see on the desktop are generated by VWS and are numerous gauges, graphs etc, but I don't believe any of the tags per se can be displayed there. As was mentioned, the htx page is converted to html by the Internet section of VWS on the db update schedule you set and it's then available for display, but not on the desktop. I have a number of gauges and graphs, meters etc. on the console display that don't get posted to the website and I use them for test and comparison as it appears you want to do.
You could create an htx page and let it convert to something like test.html and read it locally, I've got a junk page that I use for that purpose and when I'm working with other websites I put things out there that aren't necessarily for public viewing, but you don't have to FTP that page. In fact, I just copied all the ch1 tags at the bottom of this page and put it out there
http://chapalaweather.net/currenttemps.htmAs for editing, that's a long, complex and painful process. Readings appear in numerous files and data bases. The large main db is dbase.csv and contains all the readings as they are recorded and generates the graphs etc. But, a monthly high tag, for example, is pulled from a bin file that might look like 2012_01_29.bin and is edited by going to the Settings menu, Recall Daily, Monthly etc archive and then you have to learn the logic of the readings etc. and to be honest there is nothing documented that will help. For me it's been over 5 years of daily arm wrestling with it to try to outguess what it's doing. I just did a Properties search on my VWS file and it contains 6653 files, a number are website related, but a large number are standard VWS generated files and some interact, mostly the rainfall files for Daily, Montly, Yearly and gosh help you if they need to be modified.
Finally, the ultimate crash is when the dbase.csv file loses it's date/time column. All the data is still there, but about once a year I've had it suddenly wipe out all the day, date, time column numbers and you have to go in and rebuild those in large part manually. Don't know why it happens, but I live in fear.
