G'day Davmor!
Don't have time to address rumours or conspiracy theories but . .
1. What is the current/latest version of Cadsoft Build?
afaik, 7.2
2. Can you still buy or upgrade to Build?
eBay or privately maybe. Just make sure you get the appropriate dongle.
3. what about AP Design? (is this a Cadsoft product?)
Yes, originally called AutoPlan (launched here in Queensland in the mid80's I believe) until Autodesk decided they wanted a monopoly on the prefix . . . last version was 12.2 afaik. By then it had been translated into 6 or 7 languages, I believe. It harnessed the power of AutoCAD specifically for 3D architectural design & documentation. Users had to have a licensed copy of Acad for it to run. I recall reading a review in Cadence or Cadalyst that stated that Brian's layer management tools were by far the best they'd ever seen. (although it's 20yo technology, it still leaves Env's View Filter for dead . . . )
Then in the mid90's Autodesk licensed the AutoCAD engine to Cadsoft, enabling Cadsoft to market Build! - a standalone programme that offered many of the features enjoyed by AP users.
4. Is there general info on these products anywhere on the web?
Very little these days. Cadsoft seems to have tried to erase it from memory. Even a quick search of cadalyst.com gave few results but
http://www.cadsoft1.com/pdf/Cadsoft%20Upgrade.pdfhttp://www.cadsoft.com/software_updates.php#3I don't think anything has been done on either programme since mid-2004
For a company with lots of old AP Design files, are they compatible with Envisioneer?
You'll be able to open the 3D CAD models (dwg format) in Env but won't be able to extract any of the intelligence that's embedded. They could export all the layouts to individual dwg files then import them onto worksheets but again, no intelligence & making changes to a standard design for each client will be tedious & time consuming. There was talk of producing a migration manual to encourage AP/Build users to move to Env but . . . .
Merv