You are right to ask, as far as coffee machines are concerned, cleanliness is next to Godliness.
After every brewing session and before you turn the machine off, it is good to do a water back-flush.
You can buy coffee machine cleaner from Coffeeparts, and other sponsors, (standard or organic versions are available), which will soak the coffee oils away from the shower screen and similar parts, in the brew path, commonly used once a week to once a month depending on machine usage and other factors like whether or not you do a water back-flush after each brewing session. Do not put this chemical in your boiler.
The boiler can be descaled using citric acid, which you can buy from the supermarket, in the herb section usually. Do a search for the procedure. Frequency of descaling depends on the hardness of the water in your location, some of us are lucky and have relatively soft water, meaning descaling is only required maybe every 6 months or so, other places with relatively hard water may require descaling every month or two, unless you use one of the water softening filter units that are available.