milkshape is free for 30 days - so why not? and hey, if you like it you can pay the 20 dollar registration fee and get all future versions free of charge
as to the question; no, to "reskin" the ships, all you need to do is open their .mat files in UTF edit and export/import targa(.tga) files and edit them - fyi, most of the ships eg corsair,liberty,bounty,junkers,etc use TILE textures - these are easy to change, since they're not mapped onto the ship in profile, however it can be difficult to figure out which tile's which, which direction it lays in, etc
other ships, notably the junkers (whose models' names are prefixed with "co", while corsair ships are "ge" prefixed - confusing, i.m.o it shows the development team swapped these ships) and rheinlanders have full-profile textures (or as us modelers call them, "Good" textures
) - these are surprisingly low resolution for how good they look in-game
if you want to remap the ships' textures, eg where the textures are projected, you need milkshape at least - and optionally a texture mapping program like lithunwrap(free) etc that can handle ms3d files.
you may want to change material names, and internal model names with FLmodelcloner - material and internal model names must be changed if the ships or materials are going to be *additional* and not replacements - otherwise freelancer will get confused and mix them up, meaning that sometimes you see old textures/mappings othertimes you see the correct ones, depending on which model enters view first and loads an identically named(colliding) texture or model mesh