Follow the recipe for the maida one, but increase the yeast to 1 1/2 tsp or 15 gm compressed yeast

Yes you can

Chocolate Icing
Butter or margarine ½ cup (120 g)
Icing sugar, sifted 1 ¼ cup (150 g)
Cocoa powder ½ cup (50 g )
Vanilla Essence 1 tsp (5 g)
Milk ½ cup ( 120 g., approx.)

Method
1. Place butter or margarine in a bowl and beat till light.
2. Add the icing sugar, cocoa and vanilla and beat some more.
3. Add milk a little at a time and beat till smooth and holds its shape. It should also be easy to spread without applying too much pressure.

Vanilla Icing: substitute milk powder for cocoa powder.
Coffee Icing: As for Vanilla Icing, substituting 2 tbsp. of very strong black coffee for vanilla essence.

Strawberry Icing: As for Vanilla Icing, substituting strawberry essence for vanilla and adding permitted food coloring.

There was a time when Hill Road in Bandra had a shop with all sorts of cake equipment. The shop was called Cheap Jack.
Crawford market also had one right on the main road near Badshah Falooda. I am afraid since it is a long time, I have forgotten the name.

In the recipe I have on site, it is just made like a batter and put into the baking tins to rise. You do not do any beating after that.

The home made version of condensed milk is like rabri or khoya. You keep cooking the milk till the required consistency But you will not get it smooth.