F.A.Q.

No. The white balance is systematically redone before leaving our workshop. It is suitable for a wide majority of lighting situations. However, it is good to know how to redo it, as explained here (hyperlink to white balance instructions) - see gray card
You can use this new white balance in P, Tv, Av, and M modes. It is not taken into account in the full auto mode (green square) and in custom modes, such as portrait, macro, etc., which are more fitting for a compact camera than a DSLR. If you want to photograph with the least constraints possible, use the P mode which is the green square mode without the automation of ISO setting.

No. Removing glass in the optical path changes the path of light rays by about 1/3 of the thickness of said glass, fooling the Autofocus sensor. On cameras prior to the 400D, the blur is pronounced (thick filter removed), from the 400D onwards, the blur is less pronounced (thin filter removed) but it is real and cannot satisfy a demanding user unless you stop down to at least F/8. Note that adding a Clip filter on a totally modded camera changes nothing regarding AF since the AF sensor is located downstream of the filter.

There are several possible mods. The most radical - and the one that allows capturing the widest light spectrum - is total modding, meaning the original anti-IR filter is removed and not replaced. It is the least expensive mod but the downside is the loss of Autofocus and the loss of the ability to take conventional daytime photos (due to the significant influx of Infra-red rays dazzling the sensor, colors are impossible to reproduce faithfully).
The versatile alternative is to replace the original filter with another filter, allowing the desired spectrum to pass while still cutting off the near-infrared, which allows continuing to photograph normal subjects conventionally (via a new white balance).