Extensions for a steel frame house

Hello all,

Our current home is a double storey, 21yr old steel frame home and while the ground floor layout is perfect for us, we would like to extend the bedrooms on the upper floor and create a landing upstairs in place of the narrow corridor connecting the bedrooms. This would involve moving the external walls on three sides of the house and moving 4 internal walls.

Just had a few questions (please excuse the simplicity of these, we're complete novices when it comes to anything construction related!):
1) Would we need to get in an architect to assess the feasibility of this reno and draw up plans? Or could we go straight to a builder?
2) Do we need a builder with experience in steel framed housing or are the skills required and procedures for an extension pretty standard regardless of building material?
3) Is pushing the external walls out on a steel framed house even possible or are we asking for structural problems down the line?

Thanks in advance!

TCKID
Welcome to the forum
If you wish to put up a rough sketch, budget, data (ie areas) and more specific info
I am happy to help with preliminary Engineering & Construction, this may help answer your question Architect or Builder?
Merry Xmas