Everyone will have their own routines....
I wash every week or two if needed (ie if it has been out of the garage!)
You can top up the wax whenever
Once you have the wax / sealant on the car, you don't really want to polish. You need to remove the protection you have built up so you will need to use a more concentrated wash to strip the surface. Then you go through the clay / polish stuff again.
How often you leave it between polishing efforts depends on how often you top the wax up and what wax you use. As CLB noted, there are waxes that can protect for up to 12 months so with a top up of some Red Mist for example, you would just need to keep it mildly washed.
As for washing technique, most people go for the two buscket method. This is one bucket with the car wash in, and another with clean water and a grit guard in the bottom. And do NOT use a sponge. Reason being the flat surface of a sponge simply moves the grit around the car, therefore putting swirls and scratches into the surface. A wash mitt allows the grit to absorb a bit. You then use the clean bucket to rinse the dirty mitt before dipping back into the wash bucket and hitting the car again. Hope that makes sense!