most ppl can only take 1honour squads so 1 champ he can take 3 so i would say 3 champs but my point would be why would u wanna take a. him and b. that many guard units
a. He's EW, 4+ Wounds, 5 attacks (dual wield plus 4 base), 2+/4++, can sweep in termie armor and has built in teleport homer, orbital bombardment, can attack with S8 or S4 and re-roll damage against vehicles (basically tank hunters in CC), allows 3 rolls on Warlord table and can pick which to use, has 2 shot AP2 stormbolter at BS5... need I go on?
b. I don't know. Running 5 with relic blades and the banner is the most I've ever done, it's to many points in one basket but I could definitely see the argument if he could make them scoring somehow