Does multiclass ability replacement only affect parent class abilities or all class abilities?

Question

I'm about to start my first pathfinder campaign and have a few questions about multiclassing and replaced abilities.

Consider, for example, that both Monk and Rogue grant Evasion.

1. If a character has a couple levels from both, and then adds Zen Archer (which replaces evasion), does it only replace the evasion granted by the Monk, leaving the Rogue instance, or does it replace both (all instances on the character), or is this prohibited (either Monk+Rogue, or adding ZA)?
2. If it's allowed, does that mean you can take a Monk archetype that replaces [monk] evasion and a Rogue archetype that replaces [rogue] evasion at the same time?
3. If you only take the monk archetype, keeping the base Rogue levels, does the character still benefit from the Rogue evasion?

After finding and reading this question:

Pathfinder: How does taking 2 archetypes in from the same core class work?

It sounds like this scenario may be allowed, based on the answer in that question. That question however seems more general so I'm not sure it's really a duplicate, though the answer may apply to both...

Answer 1

When an archetype replaces a class feature, the archetype replaces that class feature only for that class: "Each alternate class feature presented in an archetype replaces or alters a specific class feature from its base class" (emphasis mine). In the question's example, for instance, a monk 2/rogue 2 that had taken a rogue archetype that replaced the rogue's class feature evasion would still have evasion from his levels of monk (unless, of course, he took a monk archetype that replaced that, too).

Also, to be clear, after taking levels in a class, a creature typically cannot take a class's archetype: "When a player selects a class for his character, he could choose to use the standard class features found in the class’s original description, but he could also choose to adopt an archetype" or multiple compatible archetypes.

That is, when his character gains a level—even the character's first level—the player picks for the character a class and, if the player wants, simultaneously picks one archetype or two or more compatible archetypes for that class and keeps those archetypes throughout the character's career. This means, for instance, a creature can't have 2 levels of monk then 2 more levels of zen archer monk nor can the typical creature take 2 levels of monk then add the archetype zen archer

(Note that the rules for retraining—in addition to allowing a character to abandon and adopt archetypes—also liberalizes the general archetype adoption rules above, permitting a character to skip adopting an archetype until the archetype would actually change one of his class features. If the GM's using the retraining rules at all—even if your character doesn't have an archetype—, the retraining rules are well worth reading!)

Answer 2

An archetype only modifies the features from the class it is an archetype of. It doesn't cancel all the occurrences of this features on all your classes.

For example if you are a Zen Archer Monk you get all Zen Archer Monk features (which don't involve evasion). If on top of that you are also a Rogue, you get all the Rogue features (which involve evasion).

You can also take that in reverse: get all rogue features (including evasion), then Zen Archer Monk features (which doesn't include evasion).

Whatever the way you take it you will get evasion (from Rogue), and it doesn't matter that you took another class that doesn't grant it.