Google & stuffs

Some google products has automatic updates in the product itself like Picasa & some products dont have automatic updates in the product itself like Google Talk (I couldn’t find automatic updates ) & I think such products are updated through google update manager.

My family member have installed Google Talk. I couldn’t find automatic/manual update in Google Talk. But Google Talk created 2 update entries in scheduled task & 1 update entry in msconfig - startup.

Both the update options are required i.e scheduled & startup?

Can I uncheck startup entry? I think this creates google update processor which always run as seen in the task manager, right?

Can I uncheck startup entry & keep scheduled task enabled or vice versa & Google Talk will get the updates?

I mean why startup & scheduled both, 2 ways to update?

Does this mean the startup one is for all google softwares & all the softwares will get updates & scheduled one is product specific?