Use hot water for skim milk powder

You can but the result will be much thicker than that with the whole milk, and they won't taste as good due to the reduction of fat. You could add some oil or other fat to make up the diffrence, although that will most likely change the taste as well.

Hmmm..... Well, I've lived in India for 12 yrs & this is how I make 'masala chai' or 'spiced milk tea' at home & in my restaurant-

2 cups water

1 teaspoon black tea, loose leaf (I use Tokla tea from Nepal)

1 tablespoon grated fresh ginger

10 black peppercorns, coarsely ground

500 ml full fat 'whole' milk

Sugar to taste

In a stainless steel 3L pot combine tea, water, ginger & black pepper, bring to boil over high heat. Allow to boil for about 2 minutes.

Add milk to boiling tea, again allow to come to a boil. (Watch the pot closely in case the milk begins to foam, if it does foam- stir & decrease heat a little) Allow to simmer uncovered for 6 minutes.

Remove from heat, let stand for 2 minutes. Add sugar to taste if desired & stir. Use a tea strainer to strain into cups to serve. (or serve sugar on the side so people can add sugar to their own tastes)

Some notes-

I think you are trying to make 'tulsi' chai? Tulsi = Indian holy basil

If so usually the fresh tulsi leaves (around 8-10) are added to the boiling tea mixture with around 8 green cardamoms, 2 cloves, 1/4 tsp fennel seeds, and a pinch of cumin seeds as I recall. Some Indians dry roast the whole spices to mellow the flavor a bit.

Use spices like fennel, cloves, star anise, cumin sparingly as their strong flavors can take over & give the chai a 'mouthwash' taste which isn't pleasant.