ITN- all modes: Can the costs for research, training and networking include costs of scientific visits from researchers (as lecturer) from the consortium?

These costs are part of the unit cost for research, training and network costs. They can also include costs for example of scientific visits etc. You do not have to justify the actual amounts spent on anything in the RTN costs category, but you do have to justify the relevance of the activities that will be paid for from the RTN costs.