In order to hear the shofar on Rosh Hashana you cannot go past the techum. You also cannot dig under a pile of rocks to get the shofar, or go up a tree, ride an animal, swim through water or cut it . However you can put wine or water in the shofar.

You do not stop children from blowing a shofar on Rosh Hashana rather you help them learn.

If you did not have intent to blow the shofar and you blew, you have not done your obligation.

Rosh Hashana 4:9

[For clarity we will explain our custom in blowing the Shofar]

Tekiah-- Teruah Shivarim --Tekiah

Tekiah—Shivarim-- Tekia

Tekiah—Teruah-- Tekiah

A teruah is 9 short as possible blowing as a little child sometimes cries. Shivarim is 3 short blasts of 3 teruahs each as a little child sometimes cries. A Tekiah is along blast which equals in size the middle blowing. Since we are not sure what the torah means by teruah a little cry or a longer sigh or both we do all thee ways.

If you blew a tekiah as long as two, it is still only considered one.

Even if you already prayed Mussaf when you didn’t have a shofar you still must hear the shofar.

Every person must hear the shofar.

R’ Gamlial says the right way to daven is by listening to the chazon say the Shmone Esrei.