1. the terrain graphics/color are definately a weak point of the game, so far as I know the only color mod available is the one for color blindness. Check the files sections at Apolyton.net and networknode.org to see is they hav soething new on it.
2. Vel is the only strategy guide worth aquiring. IIRC there are only 1 or 2 minor technical errors therein, and the strategy/tactic opinions in it are supported by a very large majority of players. I found part of the fun for single player was discover techniques and strategies. You can use froums like these for particular intractible questions. The strategy guide is much more important is you are going to play multiplayer.
3. I much prefer smac-x (Alien Crossfire, there are about 5 commonly used abbreviation for it) I play it about 7 to 1 vs smac. It add several new technoligies and secret projects, as weel as the aliens.
In smac-xI use the original factions more than the 7 new ones (in smac-x you can plug in any combo of the 14 factions except that if you have one alien faction, you must have both, {except on random factions when it is possible for only one to show up} you can even have duplicate faction: Hive & Hive2) there is also a faction editor included. The 5 new human faction are more extreme in strengths and weaknesses, and the AI does not play them as well as it does the original seven (of which Morgan is the one the AI plays least well, again because of its unbalence streghts and weaknessess) The AI does not seem to do as weel with the unbalanced faction, while human players are very clever is emphasising the streangths and avoiding the weaknesses)
The networknode.org specicalize is custom faction with several dozen of them, with varying levels of origianal graphics. They also have a tool and a template to help make custom factions.