I've always run a Freelancer Trader and there are positives and negatives to doing it.
I'm not in a faction, so I can't call for backup if I get into problems.
Every ship I buy, I have to finance *myself*, nobody is going to give me the credits to do it out of the goodness of their hearts and not expect to be paid back. (ok, there are a small number of people out there that will do that)
Sure, I can dock pretty much anywhere I want and buy whatever to take it elsewhere, but by the same token, if I haven't been smart enough to keep my rep reasonably clean, I can get to the appointed place and find they are hostile to me.
Case in point is 'Pueblo Bonito', I *used* to be able to dock there, but now it's hostile to me, it seems a Faction has taken it over and said it's 'not for the ordinary people'.
I *try* to play to my IFF (currently IC), so docking in certain places is oorp for me, going to try and change that to a Freelancer IFF, so that I can occasionally take a load of food to the starving Corsairs on Crete. :P
Making the load size limit even smaller would make me :( as it would put ships like the Firefly and BWT out of reach, leaving Freelancers with the 'Big Dragon' (Kusari) and 'Behemoth' (Rheinland) transports as their main choices.
From memory, commodities can bet made to work the same way as the weapons do, if you aren't friendly enough with the faction that controls the base you are on, you won't be able to buy certain things.
The only things that are buyable everywhere are the items that are needed to keep 'body and soul' together, basic foodstuffs, water and similar items.
