We use this at work and it's awesome. Solved a lot of big problems and a lot of little problems, like "works on my machine but not prod" and rebuilding your dev env when you switch machines. etc.
The one thing that became a problem was managing vmware (the plugin is a closed source one, so it was hard to debug any issue that came up with it - easily solved by writing our own open source one)
if only we had a distributed group of people, all of whom with a vested interest in figuring this out, that could help us with doing speed tests in variety of configurations…
low... a good rough base for freelancing should be triple whatever the salaried hourly rate equivalent would be (i.e. $80k/year => $40/hr, so you should be charging $120).
I do give a break if I'm charging in bulk (i.e. I have a really long term ongoing project with you and we negotiate a different rate).
The BTC support we offer is through a 3rd party merchant gateway. As a shop-owner, you are simply accepting payments via BitPay (our partner) which converts the BTC into a currency you find acceptable and deposits it into your accounts.