joker poker, e.v., and chance of bust, etc

Hi everyone,

i have been playing a game of joker poker (kings +) with a positive EV, and would like to have some questions answered (see "questions", below "assumptions")

Assumptions (used www.beatingbonuses.com to work out most of data below, and used wizard of odds to work out player edge and basic strategy):

Bank roll: $200
Player edge (e.v.) is about: + 1.926% (between 1.90% to 1.95%)
standard deviation is about: 1.10
chance of bust is about: 0.1%
bet size per hand: $0.10
hands per round of betting: 25
rounds per 10 hours: 6240 (between 600 - 640 per hour)
expected gain per 10 hours: +$300.46 (with an unlimited bank roll)
Gain to 2nd standard deviation(s): +$0.1 to + $543.03 (over 10 hour period)
expected gain^ per 10 hours: +$271.56 (with $200 starting bank roll)

Questions
expected gain^: I sort of understand that you need adequate bank-roll to effectively reduce chance of bust to nil, but why is the expected gain reduced by so much for the $200 bank roll used above?

shouldn't the expected gain be reduced to only +$300.26 for the first 10 hour block, since the chance of bust value in terms of bankroll x chance of bust, is $0.20?

thanks in advance

Kurt