My guess is that liquidity levels are managed by continually adding funds to the various exchanges in play. A well funded arb that can do this will always have the upper hand over someone who is trying to 'bootstrap' their funding.
Absolutely and this makes it really really suck if you go faster than usual and run out of funds anywhere on a Friday
This is where the leeches come into play with their 2-6% transfers and some of us actually get suckered into using them just to keep our volumes up.