Audio Systems: church speaker system, wireless mic system, volt transformer

Question
Hello;
I am volunteering to upgrade the speaker system at a church.
I found the place has 25 ceiling speakers (25W 8Ohm). It has a cheapo radio shack amp that barely keeps up and gets hot.

I have looked up the wiring of the speakers and found all of them are connected, what I believe, in parallel.

Three questions:
1-are speakers supposed to be connected in parallel (also do have transformers)?
2-I wanted to upgrade to a better Amp that handle the load. To my understanding, I would need something of at least 650 W at 8 Ohms Amp. Is that correct assumption?
3-I am interested in having a sound effect to adjust the acoustics of the sound. This is voice only, no music.
The hall is pretty big and has high ceiling; so would like to adjust the sound to a better quality. Also, would be interested to have a wireless mic system. The question is:
is there a system that house all the above in one unit, I must have a unit for each application?

What do you recommend?
Thank you.

Answer
You do not want to use a low impedance system for this. You should drive the speakers with a 70 volt amplifier and each speakers will need a 70 volt transformer unless you want to change the speakers to ones that already have transformers in them.

For you to comment negatively on something that you do not have the answers for is also unprofessional.

In my honest opinion you are over your head. The questions you are asking do no indicate that you are qualified to deal with the system you have.. If you were to consult me for system design I would be happy to do that as is my normal business. I have over 40 years in sound reinforcement experience. If you are interested then you can write me. I will give you my email address.