Brick walls, tiled steps and toddler...

I find myself to be in some state of anxiety pretty much all the time that my twenty three month old son is awake and running around. I was not this way until baby girl (who is now a month old) arrived. I am constantly worried about my little boy's safety. We moved to a two level house early this year - the bedrooms are upstairs and the other rooms are downstairs. There is a fire place with a slightly raised brick platform in front of it and beautiful mantel shelf and large mirror above it. All the rooms down stairs have tiled floors and there are two long tiled steps leading to the small foyer area and outside door. The stairs are carpeted but the floor just below it is tiled.
Every time I sit in the master bedroom to nurse baby girl, my son hangs out talking non stop, bringing things from drawers, jumping up and down the bed, fiddling around with things in the room, throwing baby girl's hat up and down and trying to catch it...and then suddenly he runs out of the room wearing baby girl's blanket over his head saying "Kanume" (peekaboo). And I panic. Right outside the room is the staircase. I tell my mother to keep an eye on my son while I am up in my room nursing baby girl. She waits for some time and sees that my son is busy playing with me inside the room. He is able to open the bedroom door even if I shut it tight or worse still he tries to pull on it and I am afraid he will fall down thud and hurt himself while I am sitting in the bed. So I don't shut the door. I imagine him tumbling down the stair case and landing on the tiled floor below and I feel panic setting in. I scream for my mom and ask her to keep an eye on him. Sometimes if she doesn't hear me I just have to abruptly stop the nursing and run to make sure he is safe and is not wandering around like a little ghost with a blanket over his head.
While he is playing downstairs he runs around the rooms - just runs - round and round - and like Charlie Chaplin goes and rams his big head on the edge of the kitchen cabinet and looks startled and starts crying when he realizes he is in pain. Two days back he ran from one end of the living room to the fire place area screaming "curever, curever" (meaning screw driver) in an excited voice and fell flat on the floor and hit his nose on the brick platform by the fire place. He had three gash marks on his swollen nose for a day - thankfully it has subsided.
I am constantly afraid he will hurt himself badly and I find it stressful to worry about this every time he runs around or when I am upstairs with baby girl unable to fully keep an eye on him. He IS quite careful on the one hand but goes into his own world of thought while climbing up and down the stairs.
Now I must come across as an over protective wimp of a mom. I thought so myself. But the other day a friend, his wife and two children visited us at night. Their son is 16m old and he was running around the house. He was running around playing and suddenly fell down and hit his forehead on the tiled step and was bleeding. They panicked on seeing the deep mark and all that blood. They were ready to go to the ER but the blood flow had stopped and it didn't look serious. My friend was insistent they go to the doctor just in case...his wife was too tired and was worried about the older child having to wait three hours in the ER for a simple cut. It was a simple cut but thankfully so. It could have been something that demanded ER attention. Now my friends say they will not move to a non carpeted house or a bi-level until both their children are a few years old.
This incident has added to my stress levels. I feel as if we are getting lucky each day in escaping with just mild bruises and bumps when kutti boy runs around the house.
When I was a child, the house we were in was a very large house but like a lot of old houses, it was not carefully planned nor child friendly. There were heavy brick steps leading to the dining room and I have had many a fall there.
How do parents in India manage this problem (this is not in any way India bashing - in case it comes across that way!)- or rather this fear? Houses are built of hard bricks and concrete. Much easier for a child to get seriously hurt if he/she bangs on the wall at an angle. No one there seems to be stressed about this issue as much as we here stress out. Are we just being over protective? I am wondering if we should move to another place before baby girl joins her brother in his antics!
I hate this feeling of stress and anxiety all day. I don't seem to be suffering from post partum depression which many people warned me about with both pregnancies. But I was not prepared to feel so anxious about the kid's safety - wondering if all of you go through this also or if am being unduly paranoid?

In response to Moppet's comment:
We do have a gate downstairs for the steps. We cannot have one upstairs - the way the stair case is designed. Even the downstairs gate is not working out a)because if I go up leaving kutti boy downstairs he cries his heart out - makes me feel very bad - especially since I have to nurse every third hour b) he has now started pulling on the gate which is even more dangerous.

Table edges have not been too much of an issue so far - I bought table cushions but it is not fitting into some of the table edges - keeps falling off. We plan to go to Home Depot this weekend and find out if we can carpet the foyer area and the tiled steps alone. Tiled floors are great to keep clean and avoid allergies for the kids.
I am not sure how we can child proof the brick platform near the fire place.

I am really curious how parents deal with this issue in India since you cannot possibly child proof all that brick and stone areas! Of course they learn by falling and it is happening here regardless of my worrying - but I just hope it is stops with minor bruises.