Unless PFS has applicable rules for this sort of thing (I wouldn't know), you'll have to wait to get the pseudodragon until your effective wizard level is 5 (as per the boon) which will be when your character level is 7 as per Eldritch Heritage. You can't get it early by taking a dumbed-down version.
Do you already have Skill Focus in some Knowledge skill? If not, then instead of going Skill Focus => Eldritch Heritage => Improved Familiar you could go Iron Will => Familiar Bond => Improved Familiar. The advantages are that you get Iron Will, you get a (normal) familiar a bit before getting your pseudodragon, and you get to use your full HD as your effective wizard level, which means you can get Improved Familiar at 5th and also that your familiar will always be a notch farther along on the familiar abilities table. The disadvantages are that you don't get Skill Focus (Knowledge(whatever)) and you aren't in line to get Improved & Greater Eldritch Heritage.
Good to know. One last thing-does the Magical Knack Trait counter the penalty from Eldritch Heritage?Unless PFS has applicable rules for this sort of thing (I wouldn't know), you'll have to wait to get the pseudodragon until your effective wizard level is 5 (as per the boon) which will be when your character level is 7 as per Eldritch Heritage. You can't get it early by taking a dumbed-down version.
Do you already have Skill Focus in some Knowledge skill? If not, then instead of going Skill Focus => Eldritch Heritage => Improved Familiar you could go Iron Will => Familiar Bond => Improved Familiar. The advantages are that you get Iron Will, you get a (normal) familiar a bit before getting your pseudodragon, and you get to use your full HD as your effective wizard level, which means you can get Improved Familiar at 5th and also that your familiar will always be a notch farther along on the familiar abilities table. The disadvantages are that you don't get Skill Focus (Knowledge(whatever)) and you aren't in line to get Improved & Greater Eldritch Heritage.
No, Magical Knack only applies to your caster level in its class, not your class level.
No, taking Improved Familiar gets you your new familiar for free. You do dismiss your old familiar, but dismissal is always free, it's replacement that costs (but not in this instance).
If your early non-Improved familiar dies or you dismiss it before that, you need to pay the usual cost to replace it, unless you just want to wait familiarlessly until you get Improved Familiar.
(1) BTW, the familiar you get initially from Familiar Bond is also free, though I don't have a FAQ for that.
(2) I'm an idiot! In my eagerness to get you to Improved Familiar I failed to look farther and see that you'd then need to take Improved Familiar Bond if you want your pseudodragon to get the usual familiar abilities like 'deliver touch spells' and 'share spells', which you probably do. So your total feat chain is one longer than with Eldritch Heritage, making that option more worth considering. (You could also get Improved Familiar Bond first and then Improved Familiar, but pseudodragons are cool.) Very sorry about that.
(3) If you have the option of changing your traits around somehow, the House of Green Mothers Pupil trait can be substituted for Iron Will as the prereq for Familiar Bond. It's in the Basic(Magic) category.