You'll probably want to take a copy of that picture with you to the supply house.
SOME supply houses- not all- sell "mast kits,' kits that include the brackets and screws. In addition, you will need two sticks of RIGID, not EMT, to go with the fittings.
I have one supply house that carries these kits. For some reason, the clerks all feign confusion when I ask... "What do you mean?" they innocently ask. I usually become a wee bit less nice and say 'the same thing you sold me last Tuesday.'
In addition, they're available from the internet. For example, Platt Electric sells their MKR-2 for $30.00.
Your PoCo will have the specs of what support they require. In certain circumstances, they MIGHT accept guy wire / aircraft cable.
Technically, you are to set the screws into the roof framing, not just the roof decking. Good luck finding it! In any event, take extra care in sealing the screws, or you'll be paying to have the roof fixed.
In practice, line crews are usually happily surprised to find a mast with additional support.
FWIW, when I do such a mast, I usually paint it to match the roof color.
One more note: The height you require will need more than a 10-ft. piece of conduit. I see two ways to do this: the 'legal way, and the 'better' way.
The legal way is to cut a shorter piece from a second stick, thread it, and have the coupling below the eave.
The 'better' way is to use schedule 40 galvanized water pipe. Though not listed as conduit - and thus, a technical violation- the stuff comes in 21-ft. lengths, and will let you make the mast without interruption.
