This tool does look promising!! So AO won't be a problem as far as I can see.
Will be like for other models... not a problem but taking a lot of time... Since you have a powerful computer, if you have a powerful GPU, there is maybe a way to speed-up and improve your AO backing... there is a little free software called xnormal ( http://www.xnormal.net/1.aspx )... in place of using CPU, it use GPU... look the AO backing time at http://www.xnormal.net/Images/OptixBench_AO.png ... Optix is nothing more that nvidia optix/cuda system... look at the video at http://www.youtube.com/watch?v=V-hoCUjn1wA too... specially at the end about mixing AO map with convexity map for improve final result... don't thing that there is a plug-in for Cinema4D but you can use the application like a stand-alone ( mean more load/save )...
As melody, it is a good tool but not anymore developed... not enough power for big work... but like you see, with thing like xnormal, we have already newer, more complex and more powerful tool...
As for tangents I think I will need to do them in C4D and then tweak them by hand in XSI (awful lot of work, same as for the omega...)
Well, i have discover the difficulty with rotating part in my last model... was more lazy that you... tangent on 0,0,0 , U1 on 0 and V1 on 1 ( right handiness )... GPU making all the work on the fly...
Anyway, it is very possible that everything will change soon with Rebellion... they move from shader 2.0 to shader 3.0 ... Sins devs have already post that ship will cast shadow on nearby ship, so it mean that maybe we will have a more real and complex light/shadow system...
Damn, you really think I would place 240 Hardpoints by hand? That will be a mamoth project. Sins has a max weapons limit of ?*sides*banks (so you say 15*s*b, I always thought it was 10 or 20)
Well, in my last model, there was between 230 and 240 hardpoint... since the .mesh was filled with error related to hardpoint, i have take my wings3d data ( picture below, the reference point is the coordinate of the selected hardpoint )...

copy these data, calculate the orientation matrix and edit the .mesh with notepad for each hardpoint... this was really a mammoth work... and it is only the prelude to a bigger project who will be maybe finish in a few year... a wings3d pluggin who allow import/export to the sins .mesh format ( bye-bye XSI who hate me)....
Anyway, if you have problem with hardpoint, i can edit the .mesh with notepad and add them without problem... by example, if Rebellion allow more abilities to capitalship and that you wish add a hardpoint for these new ability, i need the original .obj, the .mesh in text mode and a screenshot who show where you wish the new ability hardpoint and i will be able to edit the .mesh...
As for weapons hardpoint, it is a max of 3 weapons type... for each weapons type, 4 bank ( left-right-front-back ) with max 20 weapons hardpoint by bank... 3x4x20 = 240 ... in case of my last model, weapon0 and weapons1 are identical ( 2 barrel turret ), weapons2 are the missile/torpedo tube...
As for the B5 station, final version will be around 80k tri, without weapons... as today, the sketch have already increase from 3k to 12k... use the same method that for the sharlin... work in stage ( sketch and stage 1 : http://3.bp.blogspot.com/_EpX6GUNLABE/SrbZuvscp0I/AAAAAAAAAME/pnOM-Of7G8g/s1600/sharlin.jpg )... since the B5 station will have 3 stage like the sharlin, i can approximate the final poly count of the B5...
If you are limited on hard points you can always 'visually' compensate for a lower amount of available weapons using weapons effects etc.
The problem will not be the amount of weapons point but the amount of weapons type... Sins is limited to 3 weapons type and the defense grid from the babylon 5 station have 4 weapons type :
- twin particle array : http://images3.wikia.nocookie.net/__cb20090704012817/babylon5/images/7/77/DefenseGrid1.png
- plasma canon : http://images4.wikia.nocookie.net/__cb20090704013445/babylon5/images/d/dd/DefenseGrid2.png
- pulse canon : http://images2.wikia.nocookie.net/__cb20090704013539/babylon5/images/e/eb/DefenseGrid3.png
- interceptor : http://images1.wikia.nocookie.net/__cb20090704014537/babylon5/images/e/e3/DefenseGrid4.png
A hard choice is needed... one of them need to be removed from the usual weapons, maybe move to a ability... maybe the biggest one, the plasma canon become a ability using some AM... or a light one like the pulse canon becoming a "flak" ability... using a ability will be the only way to somehow keep the 4 weapons type of the real B5 station... well, it is a choice for the mod leader, for Tobi...
As for the fan, i will need their help too... i have no idea of how much of each weapons type there is on the station and where they are located...
@Tobi... for modeling the B5 station, i will not use for reference the ugly Mongoose model that you like ( http://i94.photobucket.com/albums/l104/urobach81/Babylon%205%20Minis/Earth%20Alliance/Babylon5.jpg ) but the one sell by SPACEart from Germany ( http://spaceart.de/videos/Babylon-5-Raumstation.mp4 )