I can surely help to answer your question. If you take the airport shuttle, yes, you will alight at Herbis and actually the walk over there is about 7-8 mins and need to cross at least 2-3 traffic junctions. The journey will take 1 hr. If you take the train (depending on which type of train, as they have limited express, express etc), you will need to travel to Shin-Osaka Station first (about 40-50mins depending on type of train) and then change a metro to get to Osaka Station (1 station, 3mins). There are lifts and escalators and so moving with luggage is not a problem as my family and I had many too! Don't worry, the hotel is right above the train station. Follow the directional signs (easily available and spotted), exit from the central gate and you will pass by a huge 7-11, Daimaru departmental store (on the left). There's a small side entrance to the hotel on the right side, from there, there are 4-5 lifts where you can take to go to the hotel reception is on the 19th storey. Do enjoy your Osaka stay!

They should have family room which provide enough space for your need