I know I'm getting in on this discussion a little late.
A freediving cert?? I don't think there is such a thing. There are different private classes and workshops I know but I never heard of any of the major agencies offering a specific c-card for skin diving. I may be wrong.
I freedove for a few years before I got certified and it made all the difference in the world. I already knew what to expect and had water skills developed prior to open water. I think people who freedive first make more confident and stronger scuba divers.
If you wanted to go the route of freedivng first the gear is somewhat different for scuba and freediving, depending on the level of freediving you want to get into. If you just want to go out and splash around and get a few abs then you could get away with an off the rack one piece attached hood chest zip 7 mil suit that they sell at Bamboo Reef. This type of suit would also be useable for open water scuba later.
One thing I need to warn you about though, don't let them talk you into buying a set of split fins for freediving, no no no, bad idea. Instead look into a set of paddle fins (no slit up the middle) or better yet go out to Bodega Bay Pro DIve and pick up a pair of Picasso Black team freediving long fins. Those are the ones you want for power and speed. They may kick your butt at first and seem impossible to use but trust me, once you get used to them they make all the difference in the world. Get the full foot style and a pair on neoprene socks to wear underneath. That's what everybody who takes freediving seriously around here does. You also want a low volume black skirted mask and a straight j tube snorkel. Avoid those snorkels with all the valves, purges and big bulbous looking things on top. They may try like hell to sell you on those but just get the simple J tube and learn how to use it.
I have to say it again:
**Split fins are absolutely useless for freediving, they do not provide enough power or positive power hook up when you need it most, to get up off the bottom. If they were that good you'd see all the competitive freedivers using them and you won't see a split fin one in any freedivers gear bag.**
The other suit I would recommend if you are really interested in doing freediving right and want to spend hours in the water is to get a specific freediving suit which is a 2 piece skin inside beavertauil style made out of a very soft and luxurious Yamamoto neoprene. They sell those out at Bodega Bay Pro Dive also. The brand they have is Riffe right now which look to be really nice. Those suits are only for freediving though. If you use them for scuba you will riun them because they are not meant to be crushed for extended periods of time.
I would get or rent some gear and get out there with some buddies. Hook up with the North Coast Divers and befriend some of the abalone divers in the club. Maybe go out to Gerstle Cove first and goof around in the calm cove and just get the dynamics down of breath hold diving. Gerstle a reserve and a no take zone, but it's a great place to get wet and practice.
Good luck