Wrong on both counts.
A MFSU can receive an infinite (well, probably 2 billion) amount of EUs per tick so long as each packet is 512 or less. You can safely put HV Solar arrays on five sides of the MFSU and it will use all five to charge up, but you will only be able to pull out 512EU/t
The change to the matter fab is different than how a MFSU works however. EU works on a request-supply basis, and right now it requests 2 billion EU per tick. That is being changed to 8192EU/t.
Right now, you can supply that 2 billion EU, so long as you do so in packets of 8192EU or less each. After the change, it will only ingest 8192 per tick.