I am a tax accountant and do corporate taxes for a living, so I have a pretty good understanding of tax law and have been watching bitcoins role in tax very closely.
Coin value growth would be appreciation, same as if you owned gold and sold it at a gain. You would have capital gains income on the growth. The IRS does perceive a difference in the two, they are taxed at different rates. Interest is just ordinary income and property would be subject to capital gains, either long term or short term, depending on how long you have held it for.
There are 2 different questions in your second paragraph, the first is if you trade it for a physical item, and the answer to that is it depends on the item. If it is something like gold or silver, then generally no, your basis would just transfer to the new property. If it is something like computer parts, then yes, that would trigger capital gains on the appreciation of the price. The other side of that question is if you use it to pay utilities or some other service, yes you would owe capital gains tax then on the appreciation of the price. It doesn't really matter if there is a conversion to fiat in there, you are still realizing the gain with the purchase of something and that triggers tax.
Sales tax is different than capital gains tax. One is based off of the purchase price of the item and the other is based off of basis you hold in whatever method your using to buy that item. Income tax really does not fit in here at all since you aren't providing service for income, but yes, using a debit cryptocard would still trigger the gains.
Hopefully that was clear enough, feel free to ask anymore questions or if there isn't something that makes sense and I can clarify.
Coin value growth would be appreciation, same as if you owned gold and sold it at a gain. You would have capital gains income on the growth. The IRS does perceive a difference in the two, they are taxed at different rates. Interest is just ordinary income and property would be subject to capital gains, either long term or short term, depending on how long you have held it for.
There are 2 different questions in your second paragraph, the first is if you trade it for a physical item, and the answer to that is it depends on the item. If it is something like gold or silver, then generally no, your basis would just transfer to the new property. If it is something like computer parts, then yes, that would trigger capital gains on the appreciation of the price. The other side of that question is if you use it to pay utilities or some other service, yes you would owe capital gains tax then on the appreciation of the price. It doesn't really matter if there is a conversion to fiat in there, you are still realizing the gain with the purchase of something and that triggers tax.
Sales tax is different than capital gains tax. One is based off of the purchase price of the item and the other is based off of basis you hold in whatever method your using to buy that item. Income tax really does not fit in here at all since you aren't providing service for income, but yes, using a debit cryptocard would still trigger the gains.
Hopefully that was clear enough, feel free to ask anymore questions or if there isn't something that makes sense and I can clarify.
You rock dude! that was concise, thank you for spelling that out for me. I learned a lot in those paragraphs, and Im sure the community appreciates that informed guidance (but will promptly ignore it!
) your expertise is sincerely appreciated. 
also, I know that little bit of advice would have cost me at least 100 dollars an hour, LOL.I mentioned income tax because I get paid in bitcoin, but lets shhhh about that here if you get my drift.
Bur dammit man, this is disappointing, I thought tax avoidance was that easy
back to the drawing board I guess.. 
I am glad to be able to help, i try to spread as much tax information as possible, because the only way we will be takrn serioisly and get shed in the right light is if we dont seem like a bunch of stealing hackers. Lol. Happy to help, feel free to reach out with questions. There are always tax deferal options, although getting paid in btc makes it tough, but putting money into a IRA could be a good option for you, or if yoir employee offers any tax deductible accounts that is an option as well.
