In pastry work, we set a lot of mousses, creams etc..with just a touch of gelatin. It helps stabilize it for molding.
Here is a link to the type of gelatin sheets most pastry chefs use. We use them because they are fast and have no risk of grainy gelatin clumps.
You can use know unflavored gelatin form the store, at a rate of about 1/2t.per gelatin sheet. Just make sure you soften it first, and add it to the curd mixture while it is still hot.
This little trick will allow your cakes to sit out much longer at room temperature without filling ooze.
If you are making a trip to the liquor store for baking supplies, I would suggest the following as a good starter kit.
Grand Marnier or Grand Gala ( Grand Gala is cheaper, and I actually prefer it for some things)
Kaluha or Tia Maria ( I prefer Tia Maria. Kaluha tastes muddy to me)
these are the most versatile liquors. Then, let your imagination run wild.
I use a lot of chambord ( raspberry), godiva ( chocolate), and buckets of cointreau ( seville orange). My current favorite is Alize, which is passionfruit.
An abosolutely wonderful new product is a vanilla infused cognac by the people who make Grand Marnier. I use it in Vanilla Cognac cake which is my absolute favorite yellow cake.
Don't overspend all at once. Pick one or two that you know you'll use and go from there.
Our prayers are with you having MIL with you. maybe you could teach her to ice cupcakes and keep her busy