All classes, gain a feat every other level.
2,4,6,8,10,12,14,16,18, or 20
On levels 4, 8, 12, and 16 when you gain an ability boost (2 ability points), you do not gain a feat. Instead you may choose a feat instead of an ability point. So you can get 2 ability points, or 2 feats, or 1 feat and one ability point.
Feats are as they existed in 3.5 and will be ruled individually when or if they are found to not mesh with the campaign.