The good news is that you have a coal boiler, and hydronics. I have changed out 6 of those yellow bast***ds this year, so don't ask me to comment on them.
PT Barnum called it correctly when he said there is one born every minute..... VERY tight feed, return, and heat exchanger locations.
Not a union in sight, a real PITA to modify to make two boilers work together.
Create a manifold for your zones OFF the damned boiler ....on a wall, for feed and return lines, AND DO NOT install the air scoop over the top of the boiler.
It can be on the wall as well. No rusty drips from stuck or corroded air purger vents.....look around, you will quickly see what I'm talking about....
I would add as many unions as you feel comfortable with, and if you are not a skilled soldering guy, consider black iron piping.
You can lay it out on the supply house floor and add as you go. Home D and Lowe's are NOT a plumbing supply house, so ask around and get the RIGHT components.
Sys 2000's all come with Honeywell Zone Valves, HOWEVER there are many other brands to use if you chose something else.
Than little computer is simply a means of extracting all the available btu's to the domestic hot water, and then become a zero start oil boiler.
If you have not had any service work done, you are a lucky camper. It should have a BMW sticker on it just like the fine German Ultimate Driving Machine (Bring More Wampum)
Lets just say that you are a lucky guy to have a LL dealer close by. Order the optional flue clean-out box, and larger hopper......makes life easier.