!. Note that Barrie says colour, not lack of colour. He also uses the word "may" in relation to green uranium glass.
2. In my 20+ years' experience, there are very few uranium glass colours that do not benefit from the use of uranium. It gives a richness that you don't see in a similar shade without uranium. Even grey glass has the benefit of a brightening of the colour. See here
http://lustrousstone.co.uk/cpg/displayimage.php?pid=892. No it won't be in colourless glass. The main and largest batch in a glass factory is clear. To reiterate, uranium salts were and are expensive, as is the case with many colorants.
3. No uranium glass doesn't always fluoresce brightly but get up close and it does in my experience and quite differently to manganese containing glass. And you get a faint reaction from further away, possibly one a camera cannot capture. In addition, a black light 150 W bulb, which is what Barrie is citing, is actually pretty useless at producing the best UV wavelength for uranium, also in my experience.