programs for hp-48g
 

programs for hp-48gx
hi, everyone,
i have been an owner of a hp-48gx for about 6 years now, and am now in the process of geting a cable so that i can download programs from the internet into my hp for use. i have got a few questions for all you experienced users out there.
one. i am more interested in structural steel, concrete and structural engineering programs in general. advice, please, on which ones to get.
two. i see a lot of programs written for the hp-49gx. can these be used on my hp-48gx? the reason i ask this is because the programs are placed in separate pages on hpcalc.org, for instance. is there something different about a hp-49gx, as compared to a hp-48gx, as far as programs are concerned.
three. i have 128k memory in my hp-48gx. do you think i need to get more memory? i already have a civil engineering pac on one of my two slots, but still have one slot available for additional memory, if required.
thanks.