Hello Rocket_Punk,
For the spline movement, I found a really great starter setup created by Nofyt. Here they have their pawn using their spline. The thread continues from there with many other implementation strategies to get you started.
For the boost, I would think maybe a timer and handle would suffice. It outputs a handle with which you can clear/invalidate the timer whenever you’re ready to do so. Here is the documentation on set timer by event.
I hope this information provides assistance.