This is a nice how to paint strip. If you insist on not using stripper and if mechanical means aren't getting it done, consider using a heat gun or a blow torch. (mentioned in my preferred order of attack.) Tough jobs require all three methods, repeatedly. Insure that any stripper used won't eat iron.
The paint on all but the hand rails looks somewhat sound. Hit it with a wire brush and if it doesn't all start flaking, your fine. Scuff it all up and just repaint it. The hand rails need to be smoothed and all rust removed. Avoid repainting with gloss if there's chunks left all over; shininess will show them better. If you want to look like it just came out of the factory, you'd have to sand blast the whole thing.
Strippers that contain methylene chloride can do the job in about an hour, while more environmentally friendly products without the chemical may take several hours to strip the surface clean.