[sjungdahl]

Plan on starting with Sprechers root beer extract.
I will be using a 3 gal corny keg with 5lb co2 and a picnic tap.
Midwest supply says to carbonate 3-5 days at 30lbs (25 for Sprechers)
And serve at 5-10 lbs
Buuuut in this forum members are saying that soda will become flat if not kept at 30lbs or so. Apparently dispensing at 30 lbs does not work so good. I've read this can be overcome by using 30-40 ft of 3/16 tubing on the picnic tap.
So, what's the deal?
Can I carbonate at 30 for 3-5 days and then turn down the co2 or do I leave it at 30 lbs and start with 40' of hose and trim shorter until I get a good serve?
Item 2 -
I also plan on using a carbonated to make 2 liter bottles of other flavors. For this can I just disconnect my co2 from the keg, carbonate couple 2 liters and then reconnect to the keg.
 

[kramerog]

My best guestimates: 25 psi and below 40F should be enough. Keep at that pressure. I would expect 20 feet to be long enough. 

[sjungdahl]

I was planning 35f