Mesmer effects stack through traits
Professor James – Mesmer
Typically movement increasments do not stack and the more powerful ones override the weaker ones. At least that’s the case on my ranger. Swiftness overrides the Signet (and Trait for pet 30% overrides swiftness). As for the health I can not say…
~This is the internet, my (or your) opinion doesn’t matter~
Generally movement boosts do not stack.
The phantasm/illusion hp boosts do stack though.