[pczeilon]

You should be OK if there was still any coolant in the tank. Don't press your luck though.
Some people have had luck with aftermarket tanks, some have not. The one in your link looks good. Price is right also.
Personally I'd reuse your cap & call it good. You don't need to mess with poor fit. Quite rare for the factory one to fail.

Coolant is a dealer item. $15ish from the discounters but then you have shipping... Volvo actually uses one of the more basic coolants. This has been covered in detail before in other threads. The bottom line is this. Use Volvo if it's readily available. If you must go with an alternative, Walmart Peak or Prestone will work. Try to avoid mixing types. Flush your system out well with fresh water, drain & refill with coolant of your choice. There is a radiator drain & also a block drain just above the oil cooler.

Tank
Flush Will show location of radiator drain. Not sure why it doesn't mention the block drain though. Makes life much easier.

 

[pczeilon]

The short answer is yes.
Pentosin NF is an equivalent but depending on the outlet may be more expensive than OEM.
Zerex G-05 (HOAT) would be my next non OEM choice. Can be hard to find though.
The "works in every car" are generally Dex-Cool clones (OAT) & not really speced for Volvo.

Every type uses a different technology to reach the same goal. Protect engine components with long service life. By mixing you reduce the service life & some odd combinations can even cause sediment to form. If you are replacing coolant every year or 2 it's no big deal. Any cheapo coolant will do.