looks like your caps coulda leaked. if your capper worked perfect on some then you may have got some bad cap(lazy quality control). if thats the case youre guna need to add a bit o sugar to carb the champagne yeastwont have nutin to eat
i think the bigger bottles take a bit longer to carb fully due to more fluid. give them a bit more time if they dont carb give a touch more sugar to carb.
even if it stays steady...or if you dont have a hydrometer you can wait it may even result in a better product. you should go by the hydrometer readings though.
p.s. i searched for you... the other threads about the same topic basically agree with me except for one thing... one is typically taller and skinnier then the other by a very small amount...may be a factor if you have your fridge or freezer already chosen
mostly depends on what you can get. if you have a pepsi plant that you can get them free or cheap from go ball lock and same deal coke to pin. never heard of any other real reasons to go either way...also prices depending on where you are may vary
a thorough recipe would show when during the boil to add each and how much. if it doesnt then you may have to wing it but the general layout i see most for a 60 min boil is 15 minute intervals and at 5 mins left usually evened out. if you post what type you are making someone may be able to tell...