You could load samples directly into one of FL's modules, and it should be no problem, but normally I use Kontakt as my sample player, but I'm no expert with sampling. I tend to use virtual plug in modules more often than not, things like Absynth, MusicLabs Real guitar, SuperQuartet, Jamstix virtual drummer, etc. I do have DR008 and a bunch of drum samples and setups though.

FL is a host application, meaning it hosts Vsti, DXi, and vst / dx effects. It does have built in modules as well, but I think most of us that use it normally use add on vst / dx instruments.

ASIO4All works well with my old SB live card, which I still have because it provides another midi interface and I can play soundfonts through it. The downside is it is only a 16 / 48 spec card, and the noise floor is a bit too high for good quality recording,

If you want to do a very decent soundcard on the cheap, you might consider something along the lines of the Midiman Audiophile 2496. I paid around 190 USd for mine, but today they can be had fo around 100 Usd. Mine has been in and out of 3 different computers, never a hitch. They are rock solid. I can't remember seeing very many complaints anywhere about them.

AJ