The use of "is become" here relates to verbs of motion/transition; verbs of motion would take be while other verbs would take have. There is no such grammatical distinction in English perfect forms anymore.
English began with this distinction, as did sibling languages like German.
Same here. I don't know where you're from but I got mine from Structube, no idea if it's only a Canadian thing, but it's rock solid, no angle braces, and there's a ton on heavy stuff on it.
I have a four year old phone, and unless I do something stupid I don't know why I would change.
Performance is a non issue in 2023