Yes there is always English speaking tours available all year...

Most of the tour takes place in very low light conditions, so the tour goes to great lengths to avoid steps. I doubt all of this was put in place in consideration of wheelchair users but having a group of people shuffling around in near darkness - with steps - could have been a recipe for disaster. I did not pay that much attention (apologies) to wheelchair access but I did notice (particularly as the tour ended), elevators situated to allow wheelchair access to the lower levels, for the end of tour movie. I'm sure the venue will be of more assistance. It's a very enjoyable experience.

I bought mine online through their site. You just need to make sure to select the right language tour on the day you want.

I do not have the email contact. You can book the tickets online from its website

There will be people there closer to the opening hours, if I remember correctly, it opens around 10 min before 9.30am. Enjoy your visit!

Trajan's Column is right outside the entrance of Le Domus. The museum is located in-between two churches; "Santa Maria di Loreto" and "Chiesa del Santissimo Nome di Maria al Foro Traiano".