Magus and wizard dual classing

[Micheal Smith]

So if I understand correctly if i dual class into wizard and magus, I will have two spell books 1 for the magus and 1 for the wizard). I will also have to prepare my magus spells and my wizard spells, correct? So for example if i am Magus 3/Wizard 1 with 18 int i would have the following spell:
Wizard
3x0
2x1

Magus
4x0
4x1

Assuming I got that right. Now moving on If I have the Spell Sage wizard archetype, can I use the focused spells ability to affect my magus spells? I only ask because it states
"At 1st level, once per day the spell sage's understanding of spells allows him to increase his caster level by 4 for a single spell he casts. He can do this twice per day at 8th level and three times per day at 16th level. This ability replaces arcane bond." I think I would because it says any spell I cast.

[James Risner]

In general when it says the name of the class, that is restricted to the class.

Look at Sorcerer bloodline, none of them say sorcerer. They effect all spells event non sorcerer.