Re: Goalie pickup
If this is your last add for the entire season then both Fleury and Driedger are risky as neither is technically their team's #1 goalie. That said, while you can't drop Hart in a keeper league, I'd ditch Koskinen for literally anyone. The fact that the Oilers keep running out the corpse of Mike Smith over him is telling (though, to be fair, Smith has actually been playing quite well).
If you are looking for value just this season, then I'd grab drop Koskinen for Fleury. Even if his recent play hasn't pushed him into the #1 job, the Golden Knights should split time more evenly between Fleury and Lehner once the latter is back and Vegas will provide more opportunities for wins than the Panthers. If you are looking for future value, then I'd go with Driedger. He's in a somewhat iffy position this season, because the Panthers have ten million reasons to give Bobrovsky every opportunity to solidly grab hold of the #1 job. But Driedger's a free agent at the end of the season, and should be able to sign some place with a legitimate chance to become that team's #1. Actually, if the Panther's were smart, they should trade Driedger and at least recoup something before he leaves in the offseason, and one of the most obvious landing spots for him is Edmonton (that said, a trade to a Canadian team would seriously damage his value for the rest of this season, as he would have to quarantine for two weeks before he could join his new team).
The one factor I haven't considered here is your salary cap. Fleury is making $7 million/season while Driedger's salary for this year is only $850,000 (who knows how much he'll get in free agency, but I wouldn't anticipate teams shelling out tons of money, so he's not going to sign an outrageous contract). Depending on how your cap is applied, this may be something to think about.
12-Team Yahoo H2H Keeper League (Salary cap for keepers only)
3C, 3LW, 3RW, 4D, 1 UTIL, 2G (6 BN, 6 IR+, 1 NA)
G, A, +/-, PIM, PPP, SOG, HIT, BLK / W, GAA, SV%, SHO
C - S. Aho, M. Beniers, S. Crosby, B. Jenner, L. Stankoven
LW - C. Caufield, J. Hughes, T. Moore, J. Slafkovsky, O. Tippett
RW - D. Batherson, C. Keller, A. Lafreniere, S. Reinhart
D - E. Bouchard, B. Dillon, M. Roy, M. Seider, C. York
G - J. Binnington, J. Saros, J. Swayman
IR+: T. Demko, T. Hertl, K. Johnson, G. Landeskog, J. Trouba
NA: B. Othmann