More questions about motion to and from.

[kutsuwamushi.livejournal.com]

Imagine I am at a party at Ivan's house, talking to another guest. Are these sentences correct? If not, how would you write them instead?

Я пошла к Ивану в семь. I left (set out) for the party at seven. I'm describing the moment of leaving my own house. [If this is correct, could I also say, "Я пошла сюда в семь"?]

Я пришла в восемь. I came (arrived) to the party at eight. I'm describing the moment of coming to the house where the party is being held.

Я шла к Ивану за час. I walked to Ivan's for an hour. I want to describe for how long I was moving. [Would a perfective verb be more appropriate here? If so, which one? And I've forgotten how to say "for an hour" so...]

Когда ушла из дома к Ивану, пошел дождь. After I left my house, it started to rain. [Can I use ушла even though I am currently at Ivan's house?]