Most epoxies don't need a porcupine roller, but it can help release flow trapped air up on cold days. We only use spike rollers for toppers and self levels.
Depending on the system, we get between $2.50-$6 a sq ft here (labor and mat). This is using a moisture, PH, and alkalinity resistant bottom coat, priming mid with mesh for slip resistance, and one or two color top coats. It usually ends up around 20-30 mils when done. You get what you pay for. We give a 15 year warranty on the epoxy.
All epoxie coated floors should be shot blasted to a #3 profile. Diamond grinding with a 30 grit soft bond metal will only get you a #2, but it's better than nothing. Do NOT acid wash concrete before applying epoxy. If the installer or manufacture specs acid stripping the slab as "only prep needed," it's junk epoxy and won't hold up. We blast to a #4 profile or into sand whichever comes first.
FYI, oiling your slab will ensure that NOTHING will ever correctly bond to the surface, ever. If you maybe will put in epoxy, floor covering, or ceramic tile in, oiling the slab will not let anything bond and a 100% floating system will have to be used.
I have slab core samples being sent to Mineralogy Inc. to lab test for organic surface contaminates (oils and salts). Customer wanted epoxy. After it was applied (not me, but certified applicator) the floor failed. I'm in there trying to mediate the customer and installer. The suspect contaminate is linseed oil installed by the previous owner... Tread accordingly.
(Heaven forbid...) You do need to use diesel or kerosine with the linseed oil to thin it out. It by itself it not near viscosis enough to penitrate the surface of the slab to seal it. But I do not suggest doing this, ever, even by accident. By our state building code, oil does not provide a food grade seal to the concrete slab. Check local codes before installing anything.
I'm a newbe beekeeper. By trade, I'm a surface demolition contractor, surface prep, and exposed concrete finisher. I install color and sealers to high and low sheen polished concrete surfaces, install epoxy moisture barriers, and prep concrete substrate to accept the new flooring system buy diamond grinding and shot blasting. I just keep bees because being a contractor in this economy isn't punishing enough.