Question about volumes...

During an all grain batch, do you completely drain each runnings? (add water, mix, vorlauf, drain) or do you add more sparge water when you already gather a few gallons?

And what is the ideal amount you want to collect for a 5 gallon batch? I collected 6.5 gallons last time and ended up with about 5, think this the ideal volume.

I completely drain and completely refill. You can do either and it will work. Search for "batch sparging" and "fly sparging."

Ideally, you want to collect as much as possible and boil it off. Realistically, it doesn't matter as long as you get the efficiency you want and boil it off to your target.

I run my mash down to almost a dribble, then sparge and drain to a dribble, then I boil down to my target volume, basically the same process Hal just stated, no problems yet!

The ideal amount is what works for your system. Different boil rates and the shape of the boil pot affect the evaporation rate. The only time you might want to make sure not to collect too much wort is if you are making a very light beer, and you want to boil it minimally so you don't darken it too much.

I don't completely drain the mash tun before sparging, I just wait until it slows way down.