Brookie,
i'll have to agree with Nyph, you seem a bit confused on the Betta-owning prospect. first, check the vase. if you've got a measuring cup fill it up and dump the water in the vase. how many cups can you fit? the tank should be at least a gallon, which is four quarts. a quart is four cups. if it's not a gallon, perhaps a tank is best. also, make sure the vase is wide so the Betta has many areas to get air, and make sure the plants cover as little surface area as possible.
as for your questions, i'll just answer them the way i think you meant them.
Bettas can grow to be 2-3" long without tails, but some are runty! i've seen both Grrl and Guy Bettas that are 3/4" long! these are adult fish, two years and older. Bettas commonly live around 2-3 years, but some fish (with proper, very extensive care) can live 5, 6, even 10 years! though it's incredibley rare as all Bettas are related in some way, closer than most other species, making them more prone to disease and giving them shorter lifespans. if you bred Mama dog to Brother dog, i'm pretty sure the puppies wouldn't last too long.
any conditioner is fine for Bettas =)
Betta breeding is a tough process that requires two seperate gallon tanks (one per Betta) a ten gallon tank filled roughly halfway, a very low power sponge filter, a styrofoam cup, meds, bloodworms, a breeder trap, silk plants and the Bettas. first, introduce the male to the tank, best in the morning. let him be for 12 hours, then introduce the female in the breeder trap. let them flare and show off until the next morning, then introduce the female. have the plants bunched in a corner for the female to hide in if she gets scared. remove the female if either fish exhibits extreme stress, illness, or is being bullied too much. nips and nibbles and headbutts are fine. wait 24 hours, if the male hasn't got a nest or the female is not submissive (vertical breeding bars, swimming head down, under the nest, etc etc) let them be together in the tank for no longer than 48 hours, unless they decide to start spawning on hour 48. remove the female immediately (or, if you aren't there when the spawn happens, shortly thereafter) after they spawn and treat her for any nips. leave Daddy to guard his nest, but remove him after the fry start free-swimming. at this stage turn off the filter as well, and do regular partial changes. fish out dead fry daily, it may happen, don't let they're sibs die from the ammonia shock. feed them crushed adult-foods, small live foods, or specially formulated fry foods. you'll also need to seperate females and males at around 2-3 months, gallon tanks or jars for males and large tanks for females. if you can't get the tanks, large 10-20g sterlite bins outfitted with sponge filters will work just as well.
=) but that's just my version of Betta-breeding, take Kossy's advice and everyone elses as well, and be sure you do only what you think will work. fish-keeping is a hobby that requires more thinking and learning and mistake making then other hobbies =)
