maintenance funds

[Frazraa]

Hello there,
Urgent advice required please.

i am planning to apply family visit visa for my parents and sister from Pakistan to UK. I am on tier1 general and got every thing ready but not sure about finances. i got my own house and no problem for managing anything.
How much my parents should have funds to support themselves ?
how much should I have to support them ?
My father have £5K and some property on my mother's name while my sister is dependant on my father and me.
whats minimum time period to have money in accounts.
whats chances to get visa ?
what document should i inclosed to prove my relation

any advice