familiar and improved familiar

[Shadowscale]

I know one can take wild cohort to gain a slightly weaker version of the druid's animal companion, but is there a way to gain a familiar or to switch out wild cohort for this like you can use the variant class feature to swap your familiar for an animal companion? Would you be allowed to take improved familiar on top of all of this?

[Crake]

I know one can take wild cohort to gain a slightly weaker version of the druid's animal companion, but is there a way to gain a familiar or to switch out wild cohort for this like you can use the variant class feature to swap your familiar for an animal companion? Would you be allowed to take improved familiar on top of all of this?

The obtain familiar feat from complete arcane simply requires an arcane caster level of 3 (or 5, i cant remember) (and 4 ranks in knowledge arcana), and is generally actually seen as better than the class based familiars, because it's exactly the same, except it's tied to your caster level, not class level, so it continues to progress even when you take prestige classes. And yes, you can take improved familiar to improve it