1. Interface the memory using a controller. It depends on: memory type (SRAM, SDRAM, DDR, DDR2, etc), then there are several posibilities:
a) Write Your own memory controller.
b) Use the available ipcore (opencore or bought one)
c) Use special tool made by Your FPGA vendor. E.g. Xilinx offers MIG.
2. Thats kind of a stupid question. Process data as You need, do some logic to solve Your tasks.
The most important part: learn how to ask a question first, then learn how to use google and finally, learn everything else.