Using an AC Transformer to power my Doorbell: I dont get it, please help!

Greetings, my 2 years old doorbell only runs for a week before it needs a recharge, probably because its cold outside. So lets use a transformer i thought. What I have: - a pushbutton next to the doorbell - an electromagnetic bell (rather old) - a doorbell transformer: 8V 6.6VA (can be rewired to 12V 10VA) All of that is connected in sequence. First I read the support pages: It tells me I need a 8-24V transformer with MAX 40VA and a 25Ohms 50 Watts resistor. So I have questions: 1.) What does MAX 40VA mean? My 6.6VA is less but since 40 VA is the MAX its fine? That makes no sense, a power supply cannot have to many watts only to many volts. So I need an actual 40VA transformer as a minimum? On Jeff Bezos rather large shopping site, close to 100% of all doorbell transformer have less than 20VA and the others are DC! Also I can charge my phones tablets and all usb devices with 5 Watts, why on earth would the doorbell need 8 times as much? I dont get it, what transformer do I need and where to buy it? 2.) I am supposed to install a resistor that heats up my wall from the inside from now unto all eternity? Why is that, a resistor in that case would lower the voltage slightly so its slightly less than 8 to 24V now... what does that achieve? Why not simply tell me what transformer is needed without a resistor? 3.) What is supposed to happen when I wired it correctly? When I simply connect the doorbell instead of the pushbutton the electormagnetic bell rings permanently, so I take that out and bridge the wires where the bell was. Now the Doobell Ring light is lit dimly (much less then when ringing or blinking normaly) Is that whats supposed to happen? Leave the battery in or not? I dont wanna test the bell for long since when it really needs 40VA it will fry my transformer. Every other device I own has a badge that tells me what power supply it needs, why not this bell? I really feel let down by the explanation on how to install this doorbell, the support page does not even say if I have to leave the battery inside when using a transformer... Still hoping to get this resolved and kind regards, Martin