I would recommend only changing those things that need changing.
You may have a problem with your temp sensor that causes it to
be cranky when cold. There is a good rundown on D-jet injection
at http://www.icbm.org/erkson/ttt/engine/fuel_injection/d-jet.html
which might give you a lot of help.
Brake hoses are potentially a worse problem than calipers.

I'd give it an oil change with the highest detergent oil you can find,
drive it a while and then do a dry and wet compression test. If there
is a big difference it is probably rings. If not, it may be valves.
In any case you can use a lot of oil for what an overhaul costs and
it doesn't improve reliability a lot.

Can't comment on auto tranny - never had one in a Volvo.

Congrats on your car. I have one very much like it, babymess yellow.
(AKA the yellow peril - comp rdgs 150 35 150 150 150 - uses a quart of
oil every 40 miles. I just GOTTA get that new engine together!)
--
George Downs Bartlesville, Oklahoma