Yes, but you typically increase the supply of outstanding shares from the authorized pool rather than subtracting from the original pool. This is typically how the shares for investors work as well. So of you have 100 shares, you will create 10 for employees and then 11 for the investors, assuming both get 10% (11 is 10% of 110)

At each round, you allocate the same amount but it goes to more people so they each get less.

If you are concerned about dilution then you should probably avoid external investment. If you are successful you will typically end up with less than 20% of the company as founders, split amongst you

That actually makes more sense. I used to do 35% from the start and it seemed weird to set it aside for people who won't come in for a while.