New user with IFR 1900 questions

[wj3v41]

I have been a regular reader here on the forum but just registered officially today.
Seems like there is not a lot of info available for the IFR1900. I have downloaded the operation manual and maintenance manual and it seems to be a mixture of IFR1600 and IFR1900 combined. Anyway, I have a couple questions maybe someone here might be able to answer.

Unit passes all self tests except the first test which is the clock test. I assume the RTC module has a dead battery.

1. Are there replacements available for the DS12887 RTC module?

I see several people modifying these and adding an external battery. I could do this but want to see if there are any other options.
When I run the configuration, the runtime hours is filled with garbage. I assume this is because of the RTC module?

2. Should the power supply capacitors be changed as preventative maintenance?

3, Any other areas of concern regarding capacitors?

4. Is there a calibration document available anywhere?

5. And lastly, the spec sheet says a maximum power input of 50 watts RMS. Does this mean a peak power of 200 watts is fine? Can I test my 100 watt SSB transmitter and be safe?

I did remove the top cover just to see how things looked. It was very clean and had no dust inside. Looked almost like new.
Thanks for any info........