I've only ever seen the groom and groomsmen waiting at the front, and just the bridesmaid/s come down, then the bride (alone or being walked down by someone).

Coming into the reception, just go one at a time, or all three together (boy girl boy).

With dancing, if you want photos of the couples dancing you can organise for a female family member to come in to pair with the other groomsman, and then swap so you have pics of the bridesmaid dancing with both.

Don't stress about it.

Once you're there, no one will be paying attention to them anyway