Lots of questions! This is good!
If you plan on getting corals, get a 4 bulb T5. It does not have to be one unit, you can have 2 2 bulb fixtures.
Depending on the type of coral you don't need the CO2
. The coral that would need that are going to be for more experienced reef keepers anyway.
Don't use a canister filter, they usually are just nitrate factories anyway. Go with a sump. You can buy an overflow or make one from PVC
to keep the cost down. Going with an overflow, see what it's GPH
is rated for (or if you build your own you will need to test this) and then get a return pump that is slightly more (because you will need to deal with head loss from pumping up).
Live rock will help with the cycle process. It should speed it up.
The amount of sand will depend on how deep of a sand bed you want. I'm GUESSING around 40 or so lbs for a 2" or so dept. There are calculators out there, just search for them for your best answer.
Have fun! Be patient!