Alter Form For Free

Disguise Self is useful for changing clothing and appearances and for doing other magic at the same time, while Alter Self is useful for when people will be physically interacting with you, and there is a chance that someone will detect the illusion. Using both together allows for the most secure "false identity". Yes.

Yes, it does However, to mimic a specific person's voice, you must either use Vocal Alteration, which grants another +10 on your Disguise checks, or another special ability like the Infiltrator's Voice Mimicry, which allows you to use Disguise to change your voice.

You transform your appearance. You decide what you look like, including your height, weight, facial features, sound of your voice, hair length, coloration, and distinguishing characteristics, if any. You can make yourself appear as a member of another race, though none of your statistics change.

Disguise self is only for you, but Seeming(5th level) may be what you're looking for. Disguise self has a range of 'self', which means it cannot be cast on anyone other than yourself.

You transform your appearance. You decide what you look like, including your height, weight, facial features, sound of your voice, hair length, coloration, and distinguishing characteristics, if any. You can make yourself appear as a member of another race, though none of your statistics change.

It lasts an hour with no option for increasing the duration. Thus it would just 1 hour times however many spell slots the wizard has of 2nd level or higher.

The Disguise Self spell is an illusion spell that alters the outer appearance of the caster. Note the nuance in outer appearance because the spell does not change anything physically, only visually.A creature can actively see through your disguise. During combat, doing would only be considered as their action.