Hello Bob,
Have just come back from the tour which started on the 14th. We too had Naing who couldn't be more helpful, professional, patient, knowledgeable or passionate about his country if he tried. Alison Bisset was our Tour Manager and the 2 of them made an excellent team.
My EVisa came through within 24 hours, really easy to apply and seems to be the preferred way when you arrive at Yangon as it's advertised everywhere.
$300 should be fine, I bought a few souvenirs, a drink at most lunch stops and evenings meals but tipped our TM in Sterling.
They can be funny re: folded notes; the locals tend to keep all of the notes they use flat... some places were more fussy than others. Majority of prices were quoted in $, except the markets, but were happy to accept Kyat too.
It certainly is a full on tour (very little down time) but at a gentle pace, if that makes sense and wouldn't want any of it left out.
Naing also took us to the cave with Buddha's whilst we were in Kalaw.
Burma's gone to the top of my list for holidays, you'll have an amazing time! (make sure you have a spare battery for your camera and charge it asap after changing and take an extra memory card too; Burma's a photographers dream.
Debbie