as said above, both you and your wife need a common approach to this and stick to it or it just wont work as your 2 year old is getting a different message from each of you.
try and find a compromise approach that you are both happy with (I know easier said than done!) and then both stick to it.
as above, try putting a load of soap around the valve area, if it is leaking try tightening up the nut or putting some silicon sealant around the valve.
When you put the stans yellow tape on make sure it is REALLY pulled stretched tight so it sits completely down in the rim well, otherwise it makes it more difficult to get the tyres on (as you are slightly increasing the diameter of the rim).
Also put some neat washing up liquid on the tyre beads to reduce the friction with the rim, I found this helps.
I recently “upgraded” an aluminium frame (px sl team) to a carbon one (pro-lite). The carbon one was marginally stiffer around the bottom bracket and slightly more compliant over rough roads. It depends what aluminium to what carbon frame you are doing.
For me it wasn’t a night and day change just a slight improvement in comfort and power transfer. I wouldn’t rule out going back to a aluminium frame in the future.