What kinds of competitions are available for open participants such as me?
For the Freeskiing World Tour, 2 ways to participate:
(1) Each event has a qualifier round that anyone can enter. Top skiers from the qualifier round advance to day one of the main event... number of skiers that advance from each round depends on the event.
(2) You can also qualify via the World Tour Qualifer event in Telluride (Jan 29-30 I believe this year).. typically top 5 guys/top 3 girls at this event gain automic entry into the rest of the FWT events (ie, they skip the qualifier rounds at subsequent events and can go straight to day one of the main event).
For other regional events, typically they are open to whoever pays the registration fee... Colorado Freeride Champs, Taos Freeride, Bridger Gully are a few regional events I can think of.
Do I need to join the IFSA?
For comps on the Freeskiing World Tour, yes... you can just sign up at your first comp, don't need to sign up in advance... it was $40 last year I believe and that covered the whole season. For regional comps, depends on the comp really (I know you don't have to for the CO Freeride Champs, not sure on others). Also just an fyi on the FWT comps... registration fills up usually within the first 10 minutes it is open (registration is in early Dec I believe).
For FWT, all the info you need is here: http://www.freeskiingworldtour.com, for some regional comps: http://www.skitaos.org/freeride/, aspensnowmass.com