We are Rheem ProPartners and choose to install Rheem equipment, however, we service all brands of HVAC equipment.
Yes, it's very important. Think of annual maintenance like getting the oil changed in your car. If you don't do that every few thousand miles, your car is more susceptible to breaking down, the same is true for your air conditioner- it needs TLC as well. Your heating and air conditioning system works longer and harder for you than your car does, but we often take for granted that it's working properly.
While you might be very handy with tools, it's really best that you leave this type of maintenance to the professionals. You could inadvertently cause irreparable damage that would cost you a lot more than you would have spent by hiring an expert.
It really depends on where your inside unit is located. Generally speaking, the easier it is for us to get to it, the faster we can perform the install.
If you have a year-long media filter, you only need to have it changed once a year. If you have disposable filters, we recommend checking them once a month to see if they are dirty, or replacing them every 3 months even if you don't see dust and debris.