I believe the bolts on the Front Calipers are 19mm....
The Phillips head screws on the rotors are a "bear" to get off. I would highly advise spraying them with allot of penetrating spray. The screws go all the way through and if they are rusted into place then you will mash the head and need to drill them out.
To remove the screws 100% of the time you use a pin punch and hammer. Hold the punch at a 45 degree angle c-c-w and smack it. The screw will spin backwards or break off and allow the rotor to be removed. Everytime.
I replaced the rotors my accord a few months ago with the same PITA screws. Impact driver got two of them after serious beating. Decided to try heat for the others - came out after just a couple of smacks once they had been torched for a bit.
Standard socket sizes for working on Hondas, 8, 10, 14, 17, & 19mm. As long as you have these you can do almost anything on the van. As for removing the rotors, sometimes the screws are stuck sometimes they aren't. I just changed mine and only had to drill out one screw, all the others came out with just a little effort.