Not sure what you mean, are you talking about updates to steam,and update patches fixes for games. Even on a 512Kbps connection it never took that long to login to steam.
Anyway I guess you could just leave it up and running, and when your done send the computer into sleep mode with s1-s3 mode enabled in the bios that way it would always be stored in the ram, for a quick restart of windows and steam.
Same here. Takes a while to "connect" to the steam servers on launch but once you're in, launching games don't take that long. Not much you can do about it (other than changing your Steam settings to a higher connection settings - if you do have higher than 512K connection).