Yes, mint seeds can be scattered lightly over prepared soil.
Moisten the soil and prepare the soil for planting. Lightly scatter the seeds over the area, then cover the seeds by sprinkling soil to cover and hold the seeds in place.

Yes, mint can spread very quickly and vigorously.
When planted in the ground, the long and sprawling mint roots will sprout above ground. The growth above and below ground spreads rapidly and competes for vital nutrients and resources from other plants. For this reason it is best to plant mint in containers or in smaller garden beds with other mint varieties, since it will overtake the space it is planted in.

Yes, mint can be great for growing indoors.
Mint is one of the easier herbs for growing indoors. If it receives adequate light and water, mint can grow as a beautiful aromatic ornamental as well. Mint indoors needs as much sunlight as it can get. If a sunny area is not available, a grow light can be a helpful supplement. A healthy mint plant will need regular trimming to encourage new growth.

As the blooms turn brown, cut them off the plant and lay them out to dry. Once they dry remove the seeds by rubbing the seed head. When the seeds are completely dry, store them in a cool, dark place to plant again another season.