One question I forgot: perhaps I need to get one of the SO phones that has data capability, if I want to use that SIM and get data with any other phone? The cheapest phone doesn't have data. I did read that SO CS will enable data if you ask though, it just won't be automatic like for the other two models...but I'm not sure of this.
It is the SIM card, not the phone, that allows you to have data access, so it doesn't matter what phone you buy, i.e. AFAIK
SO simcard has "data capability", regardless of whether the phone it is in has "data capability" or not. For accessing data using a SO Simcard, see this:
(scroll down to third article)
I wonder if microSDHC cards work in it? I have a 4GB one, and apparently 4GB ones work even though they say 2GB max., but it says microSD in the 5130 specs (or are all 4GBs SDHC ones, meaning all 4GB should work?). The idea being that I might as well use it to play tunes if not so much for a phone.
SD cards (including micros) maxed out at 2GB, i.e. anything over 2 GBs is SDHC. Some older devices are not capable of reading SDHC, hence the 2 GB max.