A few questions,

What is firmware, and can you get your phone flashed in the UK? Lastly, can it be taken into a store, or does it have to be sent off?

Secondly, I'm get a 128mb mmc chip. Does it matter what brand it is? Will I have to format it, and if so how do i do this, and i have 2.50 firmware, will the 256mb mmc chip work with this firmware, or will i need an upgrade?

Pardon my ignorence, and thanks alot.