If you want to change the suit color then you'll have to modify it's textures accordingly using a 3rd party program or look to borrow them from another mod that already could have done them the way you want.
As for stealth effect, it's fairly simple:
1. In object window expand Game Effects and select the Object Effect.
2. Right click in the list of effects and select new. Enter ID (something like EnchStealthPA or somesuch), Name (this will appear when you open your pipboy and check status ... I think), Type - Apparel.
3. With object effect window still open righ click the empty list, new, for effect select StealthBoyInvis ,change the magnitude to whatever you feel like, add a condition for field activation - again, rightclick new, select ConditionFunction IsSneaking, Comparison ==, Value 1 (the last two should be set by default already), ok, ok.
4. Back to object window, now you can add other effects, like IncreaseStrength, ReduceAgility or whatever you feel is right.
To make a unique armor, first open the existing armor window to use as an example, e.g. Armor TeslaPower. Now right click in armor list, select new and fill it in using the opened tesla armor as an example. Again, for ID pick something unique (and preferably meaningful), Name is what your armor will be named. Fill in it's stats and biped object (UpperBody), for object effect pick the one we created earlier (EnchStealthPA).
Now adding meshes can be slightly tricky unless you already have them ready. If not, then you can extract them using FOMM. In your tesla armor window you can see that it's biped model is using Armor\TeslaPowerArmor\outfit.NIF mesh. So open the Fallout - Meshes.bsa file and in BSA browser window navigate to meshes->armor->teslapowerarmor, select outfit.nif, extract and save it trying to use the same path as it was packed in archive. Then go back to geck and assign the biped model the one you just extracted. Repeat the same for world model and icon image.