write to segment (multiple locations) of memory

#1 Yes they do, and often expose byte enables too depending on how you setup the memory.

# 2 I recommend using the megafunction since it'll guide you to the options that are supported. After a while you will become familiar enough that you may not need to use it anymore and can instantiate the memory directly (or just infer it).

Also I recommend going to the handbook of whatever device you plan on targeting and looking at the memory block chapter. Near the beginning of that chapter it will show you all the block types you have at your disposal and the modes they can be used in. At most you will only be able to write to two memory locations concurrently but like Kaz mentioned you can work around this limitation. Another workaround is if you know the access pattern you might be able to segment your memory into separate blocks and access multiple blocks in parallel (maybe even addresses go to block 1 and odd addresses go to block 2).