if youre playing with friends, have all trades go through automatically, then the commish is the only one who can overturn a trade. im not a fan of trade voting in the leagues i play in. it slows down the process greatly and does not promote active trading. if you want trade voting, i suggest that you let all trades go through automatically, but allow 12 hours or less for objections. if the trade receives multiple objections (at least 2 or 3), then put it up for a league vote. not more than 24 hours. it forces owners to remain active if they want input. recommend that all owners to set their email settings on the website to notify them of all trades. the faster trades can be processed, the better for the league, the more it promotes trading overall.
collecting money with paypal is a good idea because it gives owners added security. add one the fee that paypal charges you to accept the payment. no sense in having the league prize pool pay the credit card fees. i also accept money order, check or cash. make it easy as possible for owners to pay you the entry fee.
im not a fan of $ per transactions. its just a pain to have to keep collecting $$ throughout the season. i would suggest sending out a fees due report after each weeks fantasy game (tuesdays). give owners two weeks to pay their weekly balance, then charge a late fee or lock them out of their team until balance is paid.
i have not used fleaflicker.com, but i am using it for one of my personal leagues this season to give it a shot.