Answer:
Following are the response:
1) The AASHTO Standard Load tab does not allow me to enter an impact factor.
A: In this case, there are 2 possible options. Either go for a user defined vehicle and scale up the loads directly at the time of definition, or the loads could be scaled up while defining the moving load case. Later option is shown in the image below.
2) These loads do not have the alternate Lane + concentrated Loads.A: Kindly refer the image below.
Once, all the required lane and vehicle loads are defined, the vehicle class command can be used to club the lane and wheel vehicles.