Rolling pre tubes question

Hi all,
A few questions from a novice tube roller. I have a Manley Stingray II and have been playing around with the pre tubes.

1. Should amp be turned all the way off, or is stand by OK when changing tubes ?
2. Tubes that have paper labels glued on them  ( Brimar CV 4033 ) OK ?
3. Can input tubes ( 12 at7's or the Brimar CV 4033's ) be substituted for the driver tubes...6414's ? I have read that       6414 can be substituted for 12 at7's but what about visa verse ? 
 I have use the Brimar CV 4033 in the 12 at7 input  spot and enjoy the sound, so was wondering about it as a driver ?
4. What tube is more impact on the sound , input or driver ?
5. Ideas for rolling  the 6414 as i do not see many around ?

Thank you. Mike
Here is an explanation for the paper labels from the Tubemonger’s website, except your labels were printed, not handwritten. I would remove them if you can:

*Each tube came with two factory stickers (click Larger Photo). A hand written individual serial number, and a handwritten number PM25525-1. Tube boxes also have a sticker with printed number PM25525-1. Tubes were factory tested and serialized for some qualification (PM25525-1), except we don’t have specific details of the qualification.

The input tube will have more impact on the sound, but both can have an effect.

It appears that the 6414 is a variant of the CV4033/12AT7 according to the Brent Jessee website, but it’s always best to check with the manufacturer before substituting. They may also recommend brands of tubes to try. Most manufacturers are happy to answer these types of questions.

6414:An industrial, computer rated dual triode,virtually the same specs as the E180CC or 7062 listed above. Unlike the E180CC, this tube was made in the USA. It is a more rugged build, with the Raytheon blackplate type sporting triple mica and military ratings. This tube is also like a 12AV7 and will work wonders in any 12AT7 spot, and may be just the ticket if you want to boost the gain of a 12AU7 circuit. The 6414 is getting very hard to find, but with a 10,000 hour heater rating you may never need a replacement. Discussion groups rate this type very highly for use in headphone amps. Stands about 1/2 inch taller than the standard 12AT7.6829:

Yeah I had the E180CC = 6414 in my LS9 Jadis Clone line stage, ( sold 3 weeks ago),, and honestly, I found no  sonic gains. 
Unit came with EH12AT7's,. I  also ran Siemens 12AT7's,, and  found no sonic gains. 
Honestly as others mention, if the unit comes with AT7's, stay with AT7's. 
The budget priced 12AT7's will sound no dif from the high priced Tele 12AT7's. 
The 12AT7 is a great pre tube, as it is so neutral sounding, = delivers the music cleanly, w/o distortions. , so stay with that tube as the designer made the circuit for exactly that tube. =  The amp will be more happy, = no disruptions down the road. Play it smart. 
If you are looking to make  tweaks try employing new capacitors, like silver or copper. 
When changing tubes turn everything off.I never heard of a tube with paper on it thats not good.Some of the best sounding tubes(6922) are Amperex.
Yep, that's them. They do sound ( to my ears) a bit more alive and dynamic then the ...12 at7's.