See, you can be on topic and only 2 parts show you are a condescending prick at heart so there is hope for you after all, . . . cough.Yup growing. About 100 tons per day falls to earth as meteorites and dust.
A whopping 1100 dump trucks per year.
I could ask where you came up with the numbers but I'm sure being the through scientist you aren't you took the weight of the earth and divided it by about 4.5B years, Right? Using the snowball earth graph it suggests the water we have came in a few 'waves' of pure snow as the heat from the planet being at 3500F on average tends to melt just about everything so even iron falls as rain rather than as a solid.
A snow storm will put out a fire that evaporates rain before it hits the ground, it melts from the stored heat inside the earth rather than the sun did the dirty deed, that also means that is where the first oceans were, where it escaped in steam vents was at the highest part of the crust and that is where the original sea life started, as the ice was evaporated into clouds again dry land began and with the rain so did the first plants right down to the lowest parts and then the snow came again but seeds can survive being frozen so the recovery was much faster. The graph also points to the south going through an ice-age while the north did not, that should be easy to prove/disprove. I don't see us being on that level really.
That is 'adding weight'.
The new land created in Hawaii is redistributing that weight. In your world of the crusting subducting as fast as the rifts expand you might run into a problem when it comes to lava and the gasses that come out as they would have to be replaced without the crust dipping down. In a ball that is connected when you take some liquid out and create a 'bump' that has to be replaced. and if it heats up and cools down at a rate that varies. When the core is as cold as outer space what will the dia. of the earth be?